Initial scopone scientifico backend

Multiplayer scopone scientifico backend on the kaya framework:

- OIDC login (kaya-oidc), session-backed WebSocket auth
- Pure rules engine (forced captures, scopa, primiera scoring) with
  full-match simulation tests
- Live game state in Redis (JSON + TTL, join codes, per-game locks,
  pub/sub state push); in-memory fallback for tests
- WebSocket /ws/games/{id} for real-time play; REST lobby endpoints
  (create/join/snapshot) with hidden-hand views
- Finished matches persisted to Postgres (Tortoise + aerich) for match
  history and leaderboard endpoints
- Docker Compose stack: postgres, redis, mock-oauth2-server, db-migrate, app
- 45 tests passing; mypy clean

tests/helpers/__init__.py

@@ -0,0 +1,4 @@
+"""Test helpers package."""
+from .oidc import make_user, oidc_user, ws_users
+
+__all__ = ["make_user", "oidc_user", "ws_users"]