Replace Jotai atoms with local state, add Suspense for PPR compatibility

- Delete filterable-row, backup-schedule, integrations, and system-health
  atom files; replace with useState/useTransition + server action calls
- Replace /api/explore/discover route with discoverByGenre server action;
  refactor FilterableTitleRow to call it directly via useTransition
- Wrap PagesLayout and AuthLayout children in Suspense to fix dynamic
  rendering errors during PPR static generation; remove StoreProvider
- Sequence ExplorePage session fetch before TMDB calls to prevent
  build-time requests during static generation
- Drop unnecessary "use client" directives from dashboard and person
  components that have no client-side hooks or browser API usage
- Improve Dockerfile: add bun install layer cache mount, copy
  .next/cache from builder, reorder ENV declarations

next.config.ts

@@ -1,18 +1,16 @@
 import type { NextConfig } from "next";
 
-const imageBaseUrl = process.env.TMDB_IMAGE_BASE_URL || "";
-const imageHost = imageBaseUrl
-  ? new URL(imageBaseUrl).hostname
-  : "image.tmdb.org";
-
 const nextConfig: NextConfig = {
   output: "standalone",
   reactCompiler: true,
+  cacheComponents: true,
   images: {
     remotePatterns: [
       {
         protocol: "https",
-        hostname: imageHost,
+        hostname: process.env.TMDB_IMAGE_BASE_URL
+          ? new URL(process.env.TMDB_IMAGE_BASE_URL).hostname
+          : "image.tmdb.org",
       },
     ],
   },