fix: add async_session_maker alias in db/__init__.py for plugin imports

app/core/db/__init__.py

@@ -86,6 +86,21 @@ def get_session_factory() -> async_sessionmaker[AsyncSession]:
     return _session_factory
 
 
+# Backward-compat alias: code imports `async_session_maker` from app.core.db.
+# Behaves like the session factory — calling it returns an AsyncSession.
+# We use a wrapper class so `async with async_session_maker() as db:` works.
+class _AsyncSessionMakerWrapper:
+    """Lazy proxy for the global async_sessionmaker."""
+    def __call__(self) -> AsyncSession:
+        return get_session_factory()()
+
+    def __getattr__(self, name: str) -> Any:
+        return getattr(get_session_factory(), name)
+
+
+async_session_maker = _AsyncSessionMakerWrapper()
+
+
 async def get_db() -> AsyncGenerator[AsyncSession, None]:
     """FastAPI dependency: yield an async database session."""
     factory = get_session_factory()