fix(config): 修复切换充值渠道报错及补齐 peace_enabled 字段声明

- 在 DouyuConfigOut 与 DouyuConfigUpdate 中补齐 peace_enabled 声明与序列化
- 在 update_config 中使用 getattr(req, field, None) 安全读取属性，避免 AttributeError 导致 500
- 在 _config_out 中加入 peace_enabled 输出映射
- 增加切换充值渠道与配置更新的单元测试

tests/test_douyu_gold_recharge_channel.py

@@ -140,6 +140,32 @@ class TestDouyuGoldRechargeChannel:
 
         assert channel == {"gold_recharge_channel": "supplier_api"}
 
+    def test_update_config_switching_recharge_channel_and_peace_enabled(self):
+        from web.backend.routers.douyu import update_config
+        from web.backend.schemas import DouyuConfigUpdate
+
+        admin_user = self.session.get(User, self.task.created_by)
+
+        # 1. 切换到 supplier_api
+        req = DouyuConfigUpdate(
+            gold_recharge_channel="supplier_api",
+            peace_enabled=True,
+        )
+        res = update_config(req, db=self.session, current=admin_user)
+        dumped = res.model_dump()
+        assert dumped["gold_recharge_channel"] == "supplier_api"
+        assert dumped["peace_enabled"] is True
+
+        # 2. 切换回 wechat_qr
+        req2 = DouyuConfigUpdate(
+            gold_recharge_channel="wechat_qr",
+            peace_enabled=False,
+        )
+        res2 = update_config(req2, db=self.session, current=admin_user)
+        dumped2 = res2.model_dump()
+        assert dumped2["gold_recharge_channel"] == "wechat_qr"
+        assert dumped2["peace_enabled"] is False
+
     def test_recharge_audit_detail_includes_safe_account_identity(self):
         record_audit(
             self.session,