Initial commit: RSS platform phase 1 skeleton with code review fixes

Features:
- FastAPI + SQLAlchemy 2.0 async + PostgreSQL/pgvector + Redis backend
- Vue 3 + TypeScript + Element Plus frontend
- JWT auth with access/refresh tokens and revocation
- Admin/member RBAC
- RSS feed CRUD and article listing
- Settings management with Fernet encryption for sensitive values
- Redis distributed lock service
- Alembic initial migration
- Docker Compose development environment

Fixes from code review:
- Fix DB session leak in dependency injection
- Restrict registration to admin only
- Add default admin password warning
- Implement JWT refresh tokens and jti blacklist
- Strengthen password policy
- Use func.count for pagination totals
- Replace NullPool with AsyncAdaptedQueuePool
- Remove init_db from lifespan to enforce alembic migrations
- Add request_id middleware and logging filter
- Fix vite.config.ts env loading
- Add frontend token refresh interceptor
- Add Vue error handler

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

backend/app/core/database.py

@@ -0,0 +1,35 @@
+"""Database configuration and session management."""
+from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker, create_async_engine
+
+from app.core.config import settings
+
+engine = create_async_engine(
+    settings.DATABASE_URL,
+    echo=settings.LOG_LEVEL == "DEBUG",
+    future=True,
+    pool_size=10,
+    max_overflow=20,
+    pool_pre_ping=True,
+)
+
+AsyncSessionLocal = async_sessionmaker(
+    engine,
+    class_=AsyncSession,
+    expire_on_commit=False,
+    autoflush=False,
+    autocommit=False,
+)
+
+
+async def get_db() -> AsyncSession:
+    """Dependency for FastAPI to get async DB session."""
+    async with AsyncSessionLocal() as session:
+        try:
+            yield session
+        finally:
+            await session.close()
+
+
+async def close_db() -> None:
+    """Close database connections."""
+    await engine.dispose()