docs: add contracts package reference to CLAUDE.md

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

CLAUDE.md

@@ -33,6 +33,42 @@ NEXT_PUBLIC_UMAMI_HOST=https://analytics.c2sgmbh.de
 NEXT_PUBLIC_UMAMI_WEBSITE_ID=<website-id>
 ```
 
+## Shared Contracts Package
+
+This project uses `@c2s/payload-contracts` for the API client layer.
+
+**Architecture:**
+- `src/lib/cms.ts` — Shared PayloadClient instance (tenant: blogwoman, ID: 9)
+- `src/lib/api.ts` — API functions powered by contracts client
+- `src/lib/types.ts` — Local type aliases (simplified for component compatibility)
+
+**Contracts Repo:** `github:complexcaresolutions/payload-contracts`
+
+```typescript
+// How the API client works (src/lib/cms.ts)
+import { createPayloadClient } from "@c2s/payload-contracts/api-client"
+export const cms = createPayloadClient({
+  baseUrl: process.env.NEXT_PUBLIC_PAYLOAD_URL!,
+  tenantId: process.env.NEXT_PUBLIC_TENANT_ID!,
+})
+
+// Usage in api.ts — tenant isolation is automatic
+const page = await cms.pages.getPage("home")
+const posts = await cms.posts.getPosts({ type: "blog", limit: 10 })
+const nav = await cms.navigation.getNavigation("header")
+```
+
+**Type Bridge:** Local types in `types.ts` use simplified interfaces (e.g., `meta` instead of `seo`). The api.ts bridges between contracts types and local types via `as unknown as`. This will be cleaned up when components are aligned with real CMS types.
+
+**Block Catalog:** See `node_modules/@c2s/payload-contracts/docs/BLOCK_CATALOG.md` for all 43 block definitions.
+
+**Updating Contracts:**
+```bash
+pnpm update @c2s/payload-contracts
+# Check for work orders in node_modules/@c2s/payload-contracts/work-orders/
+```
+
+
 ## Architecture
 
 ### Directory Structure