Implement row-level security (RLS) context management for database sessions. Refactor invoice processing and reverting tasks to utilize scoped database sessions with RLS context. Update middleware to extract and set company ID from requests. Enhance task dispatching to propagate RLS context via Celery headers. Update architecture documentation to reflect RLS implementation details.

backend/core/__init__.py

@@ -10,6 +10,9 @@ from .database import (
     get_tenant_db,
     init_async_db,
     init_db,
+    scoped_async_core_db,
+    scoped_core_db,
+    set_rls_context,
 )
 from .security import (
     get_current_active_user,
@@ -25,6 +28,9 @@ __all__ = [
     "get_core_db",
     "get_async_core_db",
     "get_tenant_db",
+    "scoped_core_db",
+    "scoped_async_core_db",
+    "set_rls_context",
     "init_db",
     "init_async_db",
     "verify_token",