fix(api): 修正 stats.py 導入路徑

- src.db.database → src.db.base
- 首席架構師審查發現

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

apps/api/src/api/v1/stats.py

@@ -24,7 +24,7 @@ from sqlalchemy.ext.asyncio import AsyncSession
 
 from src.core.logging import get_logger
 from src.core.redis_client import get_redis
-from src.db.database import get_db
+from src.db.base import get_db
 from src.db.models import IncidentRecord
 from src.models.incident import IncidentStatus