deploy: Dockerfile, entrypoint, standalone output, dockerignore

next.config.mjs

@@ -1,6 +1,8 @@
 /** @type {import('next').NextConfig} */
 const nextConfig = {
   reactStrictMode: true,
+  // Minimal Docker image: the runner stage copies .next/standalone.
+  output: 'standalone',
   // RSS/Google AdSense scripts are injected safely by our own client
   // components (see src/components/ads). Keep lint from failing the build
   // on un-stulated style warnings while keeping full type checking on.