Optimize performance: batch DB ops, N+1 fixes, Suspense streaming, and Jotai best practices

- Add composite indexes on userEpisodeWatches and userMovieWatches for hot queries
- Batch episode tracking: wrap season/batch watches in single transaction (~8 queries vs 8*N)
- Fix N+1 patterns in credits, recommendations, and filmography with batch prefetch+insert
- Stream TV season hydration via Suspense instead of blocking page render
- Optimize webhook logs (per-connection LIMIT 10) and system health queries
- Merge genre filter waterfalls into single Promise.all fetch
- Migrate deprecated Jotai loadable() to unwrap()
- Replace isolated createStore()+Provider with useHydrateAtoms on root store
- Remove unnecessary atomWithStorage SSR guards (handled by Jotai internally)

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

lib/db/client.ts

@@ -45,7 +45,11 @@ function getClient() {
 
 function getDb() {
   if (!globalForDb._db) {
-    globalForDb._db = drizzle({ client: getClient(), schema, logger: drizzleLogger });
+    globalForDb._db = drizzle({
+      client: getClient(),
+      schema,
+      logger: drizzleLogger,
+    });
   }
   return globalForDb._db;
 }