fix: fehlender pydantic Import in canonical_control_routes

BaseModel Import fehlte → gesamte Datei crashte beim Import →
alle Control-Endpoints (/controls, /frameworks, /controls-count)
lieferten 404. Frontend zeigte 0 Controls.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

backend-compliance/compliance/api/canonical_control_routes.py

@@ -29,6 +29,7 @@ from typing import Any, Optional
 
 from fastapi import APIRouter, Depends, Query
 from sqlalchemy.orm import Session
+from pydantic import BaseModel
 
 from classroom_engine.database import get_db
 from compliance.api._http_errors import translate_domain_errors