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

backend/app/routers/d3fend.py

@@ -64,7 +64,7 @@ def list_defensive_techniques(
     db: Session = Depends(get_db),
     # Entry: current_user
     current_user: User = Depends(get_current_user),
-) -> list:
+) -> dict:
     """List all D3FEND defensive techniques with optional filters."""
     # Return list_defensive_techniques_svc(
     return list_defensive_techniques_svc(
@@ -102,7 +102,7 @@ def get_defenses_for_attack_technique_endpoint(
     db: Session = Depends(get_db),
     # Entry: current_user
     current_user: User = Depends(get_current_user),
-) -> list:
+) -> dict:
     """Get all D3FEND defensive techniques mapped to a given ATT&CK technique."""
     # Return get_defenses_for_attack_technique(db, mitre_id)
     return get_defenses_for_attack_technique(db, mitre_id)