fix: admin 比价记录列表兼容 user_id 为空的孤儿行

软鉴权/匿名下 pricebot 帧0 建行时 user_id 可空(见 models.comparison),admin
全看含孤儿行;但 AdminComparisonListItem.user_id 声明为必填 int,Pydantic v2
对 None 抛 ValidationError,致 GET /admin/api/comparison-records 列表接口 500。
改为 int|None(详情接口继承一并修复),并补回归测试
test_comparison_records_list_tolerates_orphan_null_user。

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

app/admin/schemas/comparison.py

@@ -13,7 +13,8 @@ class AdminComparisonListItem(BaseModel):
     model_config = ConfigDict(from_attributes=True)
 
     id: int
-    user_id: int
+    # 软鉴权/匿名下帧0 建行时 user_id 可能暂缺(见 models.comparison 注释);admin 全看含孤儿行,故可空。
+    user_id: int | None = None
     phone: str | None = None        # join User 瞬态(非 DB 列)
     nickname: str | None = None     # join User 瞬态
     business_type: str

tests/test_admin_read.py

@@ -842,6 +842,36 @@ def test_comparison_records_show_readable_device_and_rom_version(
     assert detail.json()["platforms"][0]["is_best"] is True
 
 
+def test_comparison_records_list_tolerates_orphan_null_user(
+    admin_client: TestClient, admin_token: str
+) -> None:
+    """帧0 建行但 user_id 暂缺的孤儿记录(软鉴权/匿名),admin 列表必须能序列化、不 500。"""
+    db = SessionLocal()
+    try:
+        db.add(
+            ComparisonRecord(
+                user_id=None,
+                trace_id="comparison-orphan-null-user",
+                status="success",
+                store_name="孤儿比价专用店ZZZ",
+            )
+        )
+        db.commit()
+    finally:
+        db.close()
+
+    response = admin_client.get(
+        "/admin/api/comparison-records",
+        params={"store": "孤儿比价专用店ZZZ"},
+        headers=_auth(admin_token),
+    )
+    assert response.status_code == 200, response.text
+    items = response.json()["items"]
+    assert len(items) == 1
+    assert items[0]["user_id"] is None
+    assert items[0]["trace_id"] == "comparison-orphan-null-user"
+
+
 def test_comparison_records_show_real_order_status(
     admin_client: TestClient, admin_token: str
 ) -> None: