perf: fix slow page loads and gate performance in CI

- Ship one hashed Tailwind stylesheet instead of two (one render-blocking)
- Compress responses in-app (brotli/gzip, streaming-safe) and precompress
  the node build so local and CI measurements match production
- Validate the Supabase session once per request
- Render the homepage immediately and stream public stats
- Stream a Pokedex's entries with the page instead of fetching after
  hydration, running the rows and count queries in parallel
- Shrink the avatar and offline placeholder images, fix layout shift,
  contrast, link names and missing meta descriptions
- Add Lighthouse CI (mobile + desktop) with score and metric budgets,
  bundle-size budgets in the build tests, and signed-in speed scenarios

src/app.css

@@ -0,0 +1,3 @@
+@tailwind base;
+@tailwind components;
+@tailwind utilities;