Add BlockCoined game

[protostatis]

Summary

• integrate BlockCoined V2 from upstream commit c3a9823 as an isolated app at /game/
• preserve the original 8×8 tilted board, coin assets, mobile scaling, wager flow, persisted demo credits, and river bonus swaps
• add PanicRadar navigation, SEO/sitemap metadata, analytics, Nginx routing/cache/security policy, and frontend image build support
• add game linting, 12 reducer/engine tests, and a standalone production build to CI

Validation

• npm run lint (game)
• npm test (game: 12 passed)
• npm run build (game)
• npx eslint src/components/Header.jsx (host changed file)
• npm run build (host)
• browser smoke test of menu, tilted board, swap/cascade, computer turn, and betting prompt

Notes

• gameplay remains local/demo-only; there are no accounts, purchases, rewards, wallets, leaderboards, or backend writes
• local Docker verification was unavailable because the Docker daemon is not running; the CI Docker image build remains the production-image gate