feat: 新增追问模式和iOS本地化，重构后端输出模型

backend/tests/unit/test_json_finalize.py

@@ -87,7 +87,7 @@ def test_build_instruction_no_language_constraint_when_none() -> None:
 @pytest.mark.asyncio
 async def test_finalize_json_response_returns_alias_keys() -> None:
     model = _Model(payload={"ganzhi": {"yearGanZhi": "丙午"}})
-    _, payload = await finalize_json_response(
+    _, result = await finalize_json_response(
         model=model,
         formatter=_Formatter(),
         base_messages=[],
@@ -95,4 +95,4 @@ async def test_finalize_json_response_returns_alias_keys() -> None:
         retries=0,
     )
 
-    assert payload == {"ganzhi": {"yearGanZhi": "丙午"}}
+    assert result.model_dump(mode="json", by_alias=True) == {"ganzhi": {"yearGanZhi": "丙午"}}