fix(mcp): scope fixture NullPool + suppression imports inutiles + validation enums + cleanup tests

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/tests/test_mcp.py

@@ -1,8 +1,21 @@
 import json
 import pytest
+from sqlalchemy import delete
 from app.api.mcp_server import (
     get_todos, create_todo, update_todo, postpone_todo, delete_todo,
 )
+from app.core.database import AsyncSessionLocal
+from app.models.todos import TodoItem
+
+pytestmark = pytest.mark.usefixtures("mcp_nullpool_session")
+
+
+@pytest.fixture(autouse=True)
+async def cleanup_mcp_todos():
+    yield
+    async with AsyncSessionLocal() as session:
+        await session.execute(delete(TodoItem).where(TodoItem.title.like("TEST_MCP_%")))
+        await session.commit()
 
 
 async def test_get_todos_retourne_liste_json():