fix(test): drop obsolete FC-2a deep-rejected assertion (deep now accepted in 2d-vi)

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/test_api_import_admin.py

@@ -27,12 +27,6 @@ async def client(app):
         yield c
 
 
-@pytest.mark.asyncio
-async def test_trigger_rejects_unknown_mode(client):
-    resp = await client.post("/api/import/trigger", json={"mode": "deep"})
-    assert resp.status_code == 400
-
-
 @pytest.mark.asyncio
 async def test_status_when_idle(client):
     resp = await client.get("/api/import/status")