Send Cache-Control: no-store on every page to defeat upstream caching

Every page here is personalized (session, coin balance, owned games) —
no intermediate proxy should ever cache one. Traced a report of a
stale UI (missing header content that had already shipped) to caching
somewhere between the app and the client — nginx isn't even on this
VM, the user's reverse proxy (Nginx Proxy Manager) lives on a separate
one I can't inspect. Rather than debug an opaque hop I don't control,
close it from this side: explicit no-store on every HTML/API response
except /_next/static, which keeps its normal long-lived immutable
caching since those filenames are content-hashed by the build.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QcXH24ky6zjk2UyK5oZUPH

next.config.ts

@@ -5,6 +5,20 @@ const nextConfig: NextConfig = {
   // native .node binaries, not its JS loader, causing a segfault in
   // production. Deploying with the full node_modules via `next start` is
   // simple enough for a single-VM deployment.
+
+  async headers() {
+    return [
+      {
+        // Every page is personalized (session, wallet balance, owned
+        // games) — an intermediate proxy (nginx, a CDN) has no business
+        // caching any of it. Static assets under /_next/static are
+        // content-hashed by the build and are explicitly excluded here so
+        // they keep their own long-lived caching.
+        source: "/((?!_next/static).*)",
+        headers: [{ key: "Cache-Control", value: "no-store" }],
+      },
+    ];
+  },
 };
 
 export default nextConfig;