diff --git a/src/app/(frontend)/api/news/[slug]/route.ts b/src/app/(frontend)/api/news/[slug]/route.ts
index 85d8054..aa0a9a9 100644
--- a/src/app/(frontend)/api/news/[slug]/route.ts
+++ b/src/app/(frontend)/api/news/[slug]/route.ts
@@ -3,8 +3,11 @@
 
 import { NextRequest, NextResponse } from 'next/server'
 import { getPayload } from 'payload'
+import type { Where } from 'payload'
 import config from '@payload-config'
 import type { Category, Media, Post } from '@/payload-types'
+
+type Locale = 'de' | 'en' | 'all'
 import {
   searchLimiter,
   rateLimitHeaders,
@@ -49,8 +52,8 @@ export async function GET(request: NextRequest, { params }: RouteParams) {
     const includeRelated = searchParams.get('includeRelated') !== 'false' // Default true
 
     // Validate locale
-    const validLocales = ['de', 'en']
-    const locale = localeParam && validLocales.includes(localeParam) ? localeParam : 'de'
+    const validLocales: Locale[] = ['de', 'en']
+    const locale: Locale = localeParam && validLocales.includes(localeParam as Locale) ? (localeParam as Locale) : 'de'
 
     // Parse tenant ID - REQUIRED for tenant isolation
     const tenantId = tenantParam ? parseInt(tenantParam, 10) : undefined
@@ -68,7 +71,7 @@ export async function GET(request: NextRequest, { params }: RouteParams) {
     const payload = await getPayload({ config })
 
     // Build where clause (tenant is now required)
-    const where: Record<string, unknown> = {
+    const where: Where = {
       slug: { equals: slug },
       status: { equals: 'published' },
       tenant: { equals: tenantId },
diff --git a/src/app/(frontend)/api/news/route.ts b/src/app/(frontend)/api/news/route.ts
index 5cafb18..373a144 100644
--- a/src/app/(frontend)/api/news/route.ts
+++ b/src/app/(frontend)/api/news/route.ts
@@ -3,8 +3,11 @@
 
 import { NextRequest, NextResponse } from 'next/server'
 import { getPayload } from 'payload'
+import type { Where } from 'payload'
 import config from '@payload-config'
 import type { Category, Media, Post } from '@/payload-types'
+
+type Locale = 'de' | 'en' | 'all'
 import {
   searchLimiter,
   rateLimitHeaders,
@@ -29,7 +32,7 @@ interface NewsQueryParams {
   search?: string
   year?: number
   month?: number
-  locale: string
+  locale: Locale
   page: number
   limit: number
   excludeIds?: number[]
@@ -51,7 +54,7 @@ async function getNews(payload: Awaited<ReturnType<typeof getPayload>>, params:
   } = params
 
   // Build where clause
-  const where: Record<string, unknown> = {
+  const where: Where = {
     status: { equals: 'published' },
   }
 
@@ -131,7 +134,7 @@ async function getNews(payload: Awaited<ReturnType<typeof getPayload>>, params:
   // Execute query
   return payload.find({
     collection: 'posts',
-    where,
+    where: where as Where,
     sort: '-publishedAt',
     page,
     limit,
@@ -144,16 +147,16 @@ async function getNews(payload: Awaited<ReturnType<typeof getPayload>>, params:
 async function getCategories(
   payload: Awaited<ReturnType<typeof getPayload>>,
   tenantId?: number,
-  locale: string = 'de'
+  locale: Locale = 'de'
 ) {
-  const where: Record<string, unknown> = {}
+  const where: Where = {}
   if (tenantId) {
     where.tenant = { equals: tenantId }
   }
 
   const result = await payload.find({
     collection: 'categories',
-    where,
+    where: where as Where,
     sort: 'name',
     limit: 100,
     locale,
@@ -172,7 +175,7 @@ async function getArchive(
   payload: Awaited<ReturnType<typeof getPayload>>,
   tenantId: number // Now required
 ) {
-  const where: Record<string, unknown> = {
+  const where: Where = {
     status: { equals: 'published' },
     publishedAt: { exists: true },
     tenant: { equals: tenantId },
@@ -187,7 +190,7 @@ async function getArchive(
   while (hasMore) {
     const result = await payload.find({
       collection: 'posts',
-      where,
+      where: where as Where,
       sort: '-publishedAt',
       page,
       limit: pageSize,
@@ -270,8 +273,8 @@ export async function GET(request: NextRequest) {
     const includeArchive = searchParams.get('includeArchive') === 'true'
 
     // Validate locale
-    const validLocales = ['de', 'en']
-    const locale = localeParam && validLocales.includes(localeParam) ? localeParam : 'de'
+    const validLocales: Locale[] = ['de', 'en']
+    const locale: Locale = localeParam && validLocales.includes(localeParam as Locale) ? (localeParam as Locale) : 'de'
 
     // Validate and parse types
     let types: NewsType | NewsType[] | undefined
diff --git a/src/app/(frontend)/api/team/[slug]/vcard/route.ts b/src/app/(frontend)/api/team/[slug]/vcard/route.ts
index 2be75f9..fdb06a4 100644
--- a/src/app/(frontend)/api/team/[slug]/vcard/route.ts
+++ b/src/app/(frontend)/api/team/[slug]/vcard/route.ts
@@ -50,7 +50,7 @@ export async function GET(
     }
 
     // Generate vCard 3.0
-    const vcard = generateVCard(member)
+    const vcard = generateVCard(member as TeamMember)
 
     // Return as downloadable file
     const filename = `${member.slug || member.name?.toLowerCase().replace(/\s+/g, '-')}.vcf`
diff --git a/src/app/(frontend)/api/team/route.ts b/src/app/(frontend)/api/team/route.ts
index 5a7deae..bdd9766 100644
--- a/src/app/(frontend)/api/team/route.ts
+++ b/src/app/(frontend)/api/team/route.ts
@@ -1,7 +1,10 @@
 import { NextRequest, NextResponse } from 'next/server'
 import { getPayload } from 'payload'
+import type { Where } from 'payload'
 import config from '@payload-config'
 
+type Locale = 'de' | 'en' | 'all'
+
 /**
  * Team API
  *
@@ -44,10 +47,11 @@ export async function GET(request: NextRequest) {
     const limit = Math.min(parseInt(searchParams.get('limit') || '50'), 100)
     const page = parseInt(searchParams.get('page') || '1')
     const sort = searchParams.get('sort') || 'order'
-    const locale = (searchParams.get('locale') as 'de' | 'en') || 'de'
+    const localeParam = searchParams.get('locale')
+    const locale: Locale = (localeParam === 'de' || localeParam === 'en') ? localeParam : 'de'
 
     // Build where clause
-    const where: Record<string, unknown> = {
+    const where: Where = {
       tenant: { equals: parseInt(tenantId) },
       isActive: { equals: true },
     }
@@ -94,7 +98,7 @@ export async function GET(request: NextRequest) {
     // Query team members
     const result = await payload.find({
       collection: 'team',
-      where,
+      where: where as Where,
       sort: sortField,
       limit,
       page,
diff --git a/src/app/(frontend)/api/timelines/route.ts b/src/app/(frontend)/api/timelines/route.ts
index 9297146..985dd90 100644
--- a/src/app/(frontend)/api/timelines/route.ts
+++ b/src/app/(frontend)/api/timelines/route.ts
@@ -3,8 +3,11 @@
 
 import { NextRequest, NextResponse } from 'next/server'
 import { getPayload } from 'payload'
+import type { Where } from 'payload'
 import config from '@payload-config'
 import type { Media } from '@/payload-types'
+
+type Locale = 'de' | 'en' | 'all'
 import {
   searchLimiter,
   rateLimitHeaders,
@@ -127,8 +130,8 @@ export async function GET(request: NextRequest) {
     }
 
     // Validate locale
-    const validLocales = ['de', 'en']
-    const locale = localeParam && validLocales.includes(localeParam) ? localeParam : 'de'
+    const validLocales: Locale[] = ['de', 'en']
+    const locale: Locale = localeParam && validLocales.includes(localeParam as Locale) ? (localeParam as Locale) : 'de'
 
     // Validate type if provided
     if (typeParam && !TIMELINE_TYPES.includes(typeParam as TimelineType)) {
@@ -139,7 +142,7 @@ export async function GET(request: NextRequest) {
     }
 
     // Build where clause
-    const where: Record<string, unknown> = {
+    const where: Where = {
       status: { equals: 'published' },
       tenant: { equals: tenantId },
     }
@@ -160,7 +163,7 @@ export async function GET(request: NextRequest) {
     // Execute query
     const result = await payload.find({
       collection: 'timelines',
-      where,
+      where: where as Where,
       sort: '-updatedAt',
       limit: slugParam ? 1 : 100, // Single or list
       locale,
diff --git a/src/app/(frontend)/api/workflows/route.ts b/src/app/(frontend)/api/workflows/route.ts
index aead6db..6f07a5a 100644
--- a/src/app/(frontend)/api/workflows/route.ts
+++ b/src/app/(frontend)/api/workflows/route.ts
@@ -3,8 +3,11 @@
 
 import { NextRequest, NextResponse } from 'next/server'
 import { getPayload } from 'payload'
+import type { Where } from 'payload'
 import config from '@payload-config'
 import type { Media } from '@/payload-types'
+
+type Locale = 'de' | 'en' | 'all'
 import {
   searchLimiter,
   rateLimitHeaders,
@@ -122,8 +125,8 @@ export async function GET(request: NextRequest) {
     }
 
     // Validate locale
-    const validLocales = ['de', 'en']
-    const locale = localeParam && validLocales.includes(localeParam) ? localeParam : 'de'
+    const validLocales: Locale[] = ['de', 'en']
+    const locale: Locale = localeParam && validLocales.includes(localeParam as Locale) ? (localeParam as Locale) : 'de'
 
     // Validate type if provided
     if (typeParam && !WORKFLOW_TYPES.includes(typeParam as WorkflowType)) {
@@ -142,7 +145,7 @@ export async function GET(request: NextRequest) {
     }
 
     // Build where clause
-    const where: Record<string, unknown> = {
+    const where: Where = {
       status: { equals: 'published' },
       tenant: { equals: tenantId },
     }
@@ -163,7 +166,7 @@ export async function GET(request: NextRequest) {
     // Execute query
     const result = await payload.find({
       collection: 'workflows',
-      where,
+      where: where as Where,
       sort: '-updatedAt',
       limit: slugParam ? 1 : 100, // Single or list
       locale,
diff --git a/src/app/(payload)/api/email-logs/stats/route.ts b/src/app/(payload)/api/email-logs/stats/route.ts
index ae34093..340edd8 100644
--- a/src/app/(payload)/api/email-logs/stats/route.ts
+++ b/src/app/(payload)/api/email-logs/stats/route.ts
@@ -12,8 +12,10 @@
  */
 
 import { getPayload } from 'payload'
+import type { Where } from 'payload'
 import configPromise from '@payload-config'
 import { NextRequest, NextResponse } from 'next/server'
+import type { EmailLog } from '@/payload-types'
 import { logAccessDenied } from '@/lib/audit/audit-service'
 import { maskSmtpError } from '@/lib/security/data-masking'
 
@@ -89,7 +91,7 @@ export async function GET(req: NextRequest): Promise<NextResponse> {
     const periodDate = getPeriodDate(period)
 
     // Basis-Where für alle Queries
-    const baseWhere: Record<string, unknown> = {
+    const baseWhere: Where = {
       createdAt: { greater_than_equal: periodDate.toISOString() },
     }
 
@@ -101,7 +103,7 @@ export async function GET(req: NextRequest): Promise<NextResponse> {
       // Gesamt
       payload.count({
         collection: 'email-logs',
-        where: baseWhere,
+        where: baseWhere as Where,
       }),
       // Gesendet
       payload.count({
@@ -161,7 +163,7 @@ export async function GET(req: NextRequest): Promise<NextResponse> {
         successRate,
       },
       bySource: sourceStats,
-      recentFailures: recentFailed.docs.map((doc: Record<string, unknown>) => ({
+      recentFailures: recentFailed.docs.map((doc: EmailLog) => ({
         id: doc.id,
         to: doc.to,
         subject: doc.subject,
diff --git a/src/lib/email/newsletter-service.ts b/src/lib/email/newsletter-service.ts
index daf7a1f..caad40a 100644
--- a/src/lib/email/newsletter-service.ts
+++ b/src/lib/email/newsletter-service.ts
@@ -56,7 +56,7 @@ export class NewsletterService {
       email: string
       firstName?: string
       lastName?: string
-      interests?: string[]
+      interests?: ('general' | 'blog' | 'products' | 'offers' | 'events')[]
       source?: string
       ipAddress?: string
       userAgent?: string
@@ -245,12 +245,14 @@ export class NewsletterService {
       })
 
       // Tenant-ID ermitteln
-      const tenantId = typeof subscriber.tenant === 'object'
+      const tenantId = typeof subscriber.tenant === 'object' && subscriber.tenant
         ? subscriber.tenant.id
         : subscriber.tenant
 
       // Willkommens-E-Mail senden
-      await this.sendWelcomeEmail(tenantId as number, subscriber)
+      if (tenantId) {
+        await this.sendWelcomeEmail(tenantId as number, subscriber)
+      }
 
       return {
         success: true,
@@ -308,7 +310,7 @@ export class NewsletterService {
       }
 
       // Tenant-ID ermitteln
-      const tenantId = typeof subscriber.tenant === 'object'
+      const tenantId = typeof subscriber.tenant === 'object' && subscriber.tenant
         ? subscriber.tenant.id
         : subscriber.tenant
 
diff --git a/src/payload.config.ts b/src/payload.config.ts
index 5e1f32f..b1c285a 100644
--- a/src/payload.config.ts
+++ b/src/payload.config.ts
@@ -308,12 +308,12 @@ export default buildConfig({
       // Fix für TypeScript Types Generation - das Plugin braucht explizite relationTo Angaben
       redirectRelationships: ['pages'],
       formSubmissionOverrides: {
-        ...formSubmissionOverrides,
+        ...(formSubmissionOverrides as Record<string, unknown>),
         hooks: {
           beforeChange: [formSubmissionBeforeChange],
           afterChange: [sendFormNotification],
         },
-      },
+      } as Parameters<typeof formBuilderPlugin>[0]['formSubmissionOverrides'],
     }),
     redirectsPlugin({
       collections: ['pages'],
@@ -330,10 +330,6 @@ export default buildConfig({
         title: 'Payload CMS API',
         version: '1.0.0',
         description: 'Multi-Tenant CMS API für porwoll.de, complexcaresolutions.de, gunshin.de und zweitmein.ng',
-        contact: {
-          name: 'C2S GmbH',
-          url: 'https://complexcaresolutions.de',
-        },
       },
     }),
     // Swagger UI unter /api/docs