feat: Initial commit for OnEver Drive centralized backup system with Windows PyQt6 agent and Proxmox LXC deployment

backend/app/core/database.py

@@ -0,0 +1,34 @@
+from sqlalchemy.ext.asyncio import create_async_engine, AsyncSession, async_sessionmaker
+from sqlalchemy.orm import declarative_base
+from app.core.config import settings
+
+# Configure async engine
+engine = create_async_engine(
+    settings.DATABASE_URL,
+    echo=False,
+    future=True,
+    # SQLite-specific optimization if running SQLite
+    connect_args={"check_same_thread": False} if "sqlite" in settings.DATABASE_URL else {}
+)
+
+AsyncSessionLocal = async_sessionmaker(
+    bind=engine,
+    class_=AsyncSession,
+    expire_on_commit=False,
+    autoflush=False
+)
+
+Base = declarative_base()
+
+async def get_db():
+    """FastAPI dependency for obtaining async database sessions."""
+    async with AsyncSessionLocal() as session:
+        try:
+            yield session
+        finally:
+            await session.close()
+
+async def init_db():
+    """Initializes database tables if they do not already exist."""
+    async with engine.begin() as conn:
+        await conn.run_sync(Base.metadata.create_all)