fix(routers+imports): fix missing DetectionRule import and correct -> list return type annotations that actually return paginated dicts

backend/app/routers/osint.py

@@ -97,7 +97,7 @@ def list_osint_items(
     db: Session = Depends(get_db),
     # Entry: user
     user: User = Depends(get_current_user),
-) -> list:
+) -> dict:
     """List OSINT items with optional filters.
 
     Args: