feat: initial BantayCam scaffold

- FastAPI backend with async SQLAlchemy
- Camera RTSP management (add, start, stop)
- Vehicle detection (YOLO + fast-alpr)
  - Type: car, motorcycle, truck, jeepney
  - Color detection (HSV)
  - License plate OCR
  - Motorcycle person count
- Face detection + InsightFace ArcFace embedding
- pgvector identity grouping (auto-cluster same face)
- Vehicle + person movement trail APIs
- Docker Compose with pgvector/pg16
- Models: Camera, VehicleIdentity, VehicleEvent, PersonIdentity, FaceEvent

backend/app/core/database.py

@@ -0,0 +1,34 @@
+from sqlalchemy.ext.asyncio import create_async_engine, AsyncSession, async_sessionmaker
+from sqlalchemy.orm import DeclarativeBase
+from app.core.config import settings
+
+
+engine = create_async_engine(
+    settings.DATABASE_URL,
+    echo=settings.DEBUG,
+    pool_pre_ping=True,
+)
+
+AsyncSessionLocal = async_sessionmaker(
+    engine,
+    class_=AsyncSession,
+    expire_on_commit=False,
+)
+
+
+class Base(DeclarativeBase):
+    pass
+
+
+async def get_db():
+    async with AsyncSessionLocal() as session:
+        try:
+            yield session
+        finally:
+            await session.close()
+
+
+async def init_db():
+    """Create all tables on startup."""
+    async with engine.begin() as conn:
+        await conn.run_sync(Base.metadata.create_all)