fix: use valid UUID for requestId in CDN live URL endpoint

The requestId was being set to a string like "live-avatars-1767520170167"
which is not a valid UUID. This caused PostgreSQL to reject the insert
into the generations table.

Now uses req.requestId from the middleware which generates a proper UUID.

apps/api-service/src/routes/cdn.ts

@@ -427,7 +427,7 @@ cdnRouter.get(
         prompt,
         aspectRatio: (aspectRatio as string) || GENERATION_LIMITS.DEFAULT_ASPECT_RATIO,
         autoEnhance: normalizedAutoEnhance,
-        requestId: `live-${scope}-${Date.now()}`,
+        requestId: req.requestId,
       });
 
       if (!generation.outputImage) {