portrait-only: drop landscape rotate prompt + lock to portrait

- Remove RotatePrompt (the "rotate to landscape" overlay) — the app is portrait
  now, so it only blocked the UI.
- page.tsx: best-effort orientation lock switched landscape → portrait.
- Add Playwright-based store-screenshot + icon scripts (scripts/shots.js,
  game.js, icon.js); generated images are gitignored.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.gitignore

@@ -60,3 +60,7 @@ next-env.d.ts
 *.db-shm
 *.db-wal
 
+
+# store screenshot artifacts
+/scripts/shots/
+/store-assets/