fix: 添加创建Claude账户时缺失的useUnifiedUserAgent字段处理

- 在 /admin/claude-accounts POST 路由中添加 useUnifiedUserAgent 参数解构
- 将 useUnifiedUserAgent 参数传递给 claudeAccountService.createAccount() 方法
- 保持与前端 AccountForm.vue 和服务层 claudeAccountService.js 的一致性

src/routes/admin.js

@@ -1902,7 +1902,8 @@ router.post('/claude-accounts', authenticateAdmin, async (req, res) => {
       priority,
       groupId,
       groupIds,
-      autoStopOnWarning
+      autoStopOnWarning,
+      useUnifiedUserAgent
     } = req.body
 
     if (!name) {
@@ -1942,7 +1943,8 @@ router.post('/claude-accounts', authenticateAdmin, async (req, res) => {
       accountType: accountType || 'shared', // 默认为共享类型
       platform,
       priority: priority || 50, // 默认优先级为50
-      autoStopOnWarning: autoStopOnWarning === true // 默认为false
+      autoStopOnWarning: autoStopOnWarning === true, // 默认为false
+      useUnifiedUserAgent: useUnifiedUserAgent === true // 默认为false
     })
 
     // 如果是分组类型，将账户添加到分组