fix: 优化同步上游模型的写回载荷，克隆并保留远端返回的所有非敏感 credentials，避免丢失 compact_model_mapping 等其它配置

backend/app/routers/websites.py

@@ -1391,8 +1391,12 @@ def sync_website_accounts_upstream_models(
                 continue
 
             # 1. 先安全修复 base_url (不依赖同步模型结果)
+            # 在 remote_acc.get("credentials") 基础上进行修改，保留其他非敏感 credentials (例如 compact_model_mapping)
+            current_creds = dict(remote_acc.get("credentials") or {})
+            current_creds["base_url"] = upstream_base_url
+
             try:
-                c.update_account(aid, {"credentials": {"base_url": upstream_base_url}})
+                c.update_account(aid, {"credentials": current_creds})
             except Exception as e:
                 items.append(SyncUpstreamModelsItem(
                     account_id=aid,
@@ -1421,11 +1425,10 @@ def sync_website_accounts_upstream_models(
                     ))
                     continue
 
-                # 3. 模型同步成功后，写回 base_url 和 model_mapping
-                c.update_account(aid, {"credentials": {
-                    "base_url": upstream_base_url,
-                    "model_mapping": {m: m for m in valid_models}
-                }})
+                # 3. 模型同步成功后，在 current_creds 基础上替换 model_mapping 并写回
+                updated_creds = dict(current_creds)
+                updated_creds["model_mapping"] = {m: m for m in valid_models}
+                c.update_account(aid, {"credentials": updated_creds})
 
                 items.append(SyncUpstreamModelsItem(
                     account_id=aid,