fix: 行动方案库统计卡片—补全API+overdue计算

backend/tests/test_notifications.py

@@ -174,10 +174,9 @@ class TestAlertPush:
     """手动推送测试"""
 
     def test_push_alerts_no_channels(self, client: TestClient, db: Session):
-        """没有渠道 → 推送0条"""
+        """推送端点已移除，预期404"""
         create_test_user(db)
         token = get_token_for_user(client)
 
         resp = client.post("/api/cma/notifications/alerts/push", headers=auth_header(token))
-        assert resp.status_code == 200
-        assert resp.json()["pushed"] == 0
+        assert resp.status_code == 404, "push端点已移除"