登录任务增加代理切换次数设置

- 后端: LoginBatchRequest 增加 max_proxy_retries 字段，默认10，0=无限
- 核心: DouyuLogin 极验验证循环根据 max_proxy_retries 控制重试
- 前端: 筛选栏增加代理切换次数输入框，Tooltip 提示0=无限切换直到成功

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

web/frontend/src/api/modules.ts

@@ -56,8 +56,8 @@ export const accountApi = {
 };
 
 export const loginApi = {
-  createBatch: (account_ids: number[], max_geetest_retries?: number, concurrency?: number) =>
-    api.post<any, any>('/login/batch', { account_ids, max_geetest_retries, concurrency }),
+  createBatch: (account_ids: number[], max_geetest_retries?: number, concurrency?: number, max_proxy_retries?: number) =>
+    api.post<any, any>('/login/batch', { account_ids, max_geetest_retries, concurrency, max_proxy_retries }),
   listTasks: (batch_id?: string) =>
     api.get<any, any[]>('/login/tasks', { params: batch_id ? { batch_id } : {} }),
   stop: (batch_id: string) => api.post<any, any>(`/login/stop/${batch_id}`),