fix: correct get_db_session import in tool_instances.py

Import get_db_session from src.auth.dependencies instead of src.database.
Fixes ImportError on application startup.

apps/api/src/api/tool_instances.py

@@ -9,7 +9,7 @@ from sqlalchemy import select
 from sqlalchemy.ext.asyncio import AsyncSession
 
 from src.auth.dependencies import get_current_user_id
-from src.database import get_db_session
+from src.auth.dependencies import get_db_session
 from src.models.git_repository import GitRepository
 from src.models.project import Project
 from src.models.tool_instance import ToolInstance