feat: Initial project structure for WebTriviasMulti

- Backend: FastAPI + Python-SocketIO + SQLAlchemy
  - Models for categories, questions, game sessions, events
  - AI services for answer validation and question generation (Claude)
  - Room management with Redis
  - Game logic with stealing mechanics
  - Admin API for question management

- Frontend: React + Vite + TypeScript + Tailwind
  - 5 visual themes (DRRR, Retro, Minimal, RGB, Anime 90s)
  - Real-time game with Socket.IO
  - Achievement system
  - Replay functionality
  - Sound effects per theme

- Docker Compose for deployment
- Design documentation

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/app/models/base.py

@@ -0,0 +1,27 @@
+from sqlalchemy.ext.declarative import declarative_base
+from sqlalchemy.ext.asyncio import create_async_engine, AsyncSession
+from sqlalchemy.orm import sessionmaker
+from app.config import get_settings
+
+settings = get_settings()
+
+# Convert postgresql:// to postgresql+asyncpg://
+database_url = settings.database_url.replace(
+    "postgresql://", "postgresql+asyncpg://"
+)
+
+engine = create_async_engine(database_url, echo=True)
+
+AsyncSessionLocal = sessionmaker(
+    engine, class_=AsyncSession, expire_on_commit=False
+)
+
+Base = declarative_base()
+
+
+async def get_db():
+    async with AsyncSessionLocal() as session:
+        try:
+            yield session
+        finally:
+            await session.close()