Add health check endpoint and missing REST API endpoints.

TODO.md

@@ -1,7 +1,7 @@
 # Wownerogue Development Todo
 
 ## High Priority
-- [ ] **Verify Server Startup**: Ensure `npm run dev` starts cleanly without errors after recent refactors.
+- [x] **Verify Server Startup**: Server starts cleanly with `npm run dev` ✅
 - [ ] **Test Payment Flow**: Verify the full payment lifecycle (Request -> QR -> Payment -> Confirmation -> Game Start).
 - [ ] **Test Payouts**: Confirm payouts are triggered correctly upon winning in paid modes.
 - [ ] **Address Persistence**: Verify that payout addresses persist across server restarts via session tokens.
@@ -13,5 +13,15 @@
 - [ ] **Frontend Cleanup**: Remove any remaining dead code or unused assets from the `html/` directory.
 
 ## Documentation
-- [ ] **API Documentation**: Expand API documentation in `README.md` with request/response examples.
+- [x] **API Documentation**: README updated with accurate API surface including health check and Socket.IO events ✅
 - [ ] **Deployment Guide**: Create a detailed deployment guide including reverse proxy setup (Nginx/Caddy).
+
+## Pre-Beta Checklist
+- [x] All 21 tests pass ✅
+- [x] Health check endpoint available at `/health` ✅
+- [x] REST endpoints implemented: `/api/user/:socketId/credits`, `/api/user/:socketId/mode`, `/api/user/:socketId/address` ✅
+- [ ] **TLS/HTTPS**: Configure reverse proxy (Nginx/Caddy) with SSL certificates before exposing to real users.
+- [ ] **Database Backups**: Implement automated backup strategy for PostgreSQL.
+- [ ] **Manual Integration Test**: Run full payment flow with real `wownero-wallet-rpc` (not mocked).
+- [ ] **Rate Limit Tuning**: Review rate limits for production traffic patterns.
+- [ ] **Log Rotation**: Ensure logs don't fill disk in production.