chore: stabilize pipeline and harden infrastructure

- Harden E2E smoke tests with increased timeouts and German keyword detection
- Implement defensive body parsing in analytics relay to prevent crashes
- Refine middleware to bypass i18n logic for Server Actions
- Fix date formatting consistency and JsonLd validation

middleware.ts

@@ -14,8 +14,12 @@ export default async function middleware(request: NextRequest) {
   const { method, url, headers } = request;
   const { pathname } = request.nextUrl;
 
-  // Explicit bypass for infrastructure and Payload CMS routes to avoid locale redirects/interception
+  // Explicit bypass for infrastructure, Payload CMS, and Server Actions
+  // Next-Action header is present for all Next.js Server Actions
+  const isServerAction = headers.has('next-action');
+
   if (
+    isServerAction ||
     pathname.startsWith('/admin') ||
     pathname.startsWith('/api') ||
     pathname.startsWith('/stats') ||
@@ -55,10 +59,12 @@ export default async function middleware(request: NextRequest) {
     // Only create a new request for GET/HEAD to avoid consuming the body stream on POST/PUT
     // This resolves the "failed to pipe response" error (160k occurrences in GlitchTip)
     if (['GET', 'HEAD'].includes(request.method)) {
+      // Clone headers to ensure all Next.js internal headers (like router state) are preserved
+      const clonedHeaders = new Headers(request.headers);
+      
       effectiveRequest = new NextRequest(urlObj, {
-        headers: request.headers,
+        headers: clonedHeaders,
         method: request.method,
-        // No body for GET/HEAD
       });
 
       if (process.env.NODE_ENV !== 'production' || !process.env.CI) {