fix(youtube-analytics): fix tab-switch crash and channel selector

- Clear data state on tab switch to prevent stale data type mismatch
- Add defensive null guards in all render functions (?.stats, ?.pipeline)
- Use channel ID instead of slug for API filtering

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

src/components/admin/YouTubeAnalyticsDashboard.tsx

@@ -272,7 +272,7 @@ export const YouTubeAnalyticsDashboard: React.FC = () => {
 
   const renderPerformance = () => {
     const perfData = data as PerformanceData
-    if (!perfData) return null
+    if (!perfData?.stats) return null
 
     return (
       <>
@@ -435,7 +435,7 @@ export const YouTubeAnalyticsDashboard: React.FC = () => {
 
   const renderPipeline = () => {
     const pipeData = data as PipelineData
-    if (!pipeData) return null
+    if (!pipeData?.pipeline) return null
 
     // Group statuses for pipeline bar
     const statusGroups: Record<string, { label: string; className: string }> = {
@@ -557,7 +557,7 @@ export const YouTubeAnalyticsDashboard: React.FC = () => {
 
   const renderGoals = () => {
     const goalsData = data as GoalsData
-    if (!goalsData) return null
+    if (!goalsData?.stats) return null
 
     return (
       <>
@@ -652,7 +652,7 @@ export const YouTubeAnalyticsDashboard: React.FC = () => {
 
   const renderCommunity = () => {
     const commData = data as CommunityData
-    if (!commData) return null
+    if (!commData?.stats) return null
 
     const sentimentMax = Math.max(...Object.values(commData.sentiment))
 
@@ -765,7 +765,7 @@ export const YouTubeAnalyticsDashboard: React.FC = () => {
           >
             <option value="all">Alle Kanäle</option>
             {channels.map((ch) => (
-              <option key={ch.id} value={ch.slug}>
+              <option key={ch.id} value={ch.id}>
                 {ch.name}
               </option>
             ))}
@@ -807,7 +807,12 @@ export const YouTubeAnalyticsDashboard: React.FC = () => {
           <button
             key={tab.key}
             className={`yt-analytics__tab ${activeTab === tab.key ? 'yt-analytics__tab--active' : ''}`}
-            onClick={() => setActiveTab(tab.key)}
+            onClick={() => {
+              if (tab.key !== activeTab) {
+                setData(null)
+                setActiveTab(tab.key)
+              }
+            }}
           >
             {tab.icon}
             {tab.label}