feat: 简化用户隧道权限分配，支持多选隧道批量分配 (#8)

- 新增批量分配接口 POST /tunnel/user/batch-assign
- 支持一次选择多个隧道进行分配
- 每个隧道可单独设置限速规则
- flow/num/flowResetTime/expTime 自动从用户设置继承
- 前端表单简化为隧道多选列表+限速选择
- 已分配的隧道显示'已分配'标记且不可重复选择

vite-frontend/src/api/index.ts

@@ -46,6 +46,8 @@ export const updateTunnelOrder = (data: { tunnels: Array<{ id: number; inx: numb
 
 // 用户隧道权限管理操作 - 全部使用POST请求
 export const assignUserTunnel = (data: any) => Network.post("/tunnel/user/assign", data);
+export const batchAssignUserTunnel = (data: { userId: number; tunnels: Array<{ tunnelId: number; speedId?: number | null }> }) => 
+  Network.post("/tunnel/user/batch-assign", data);
 export const getUserTunnelList = (queryData: any = {}) => Network.post("/tunnel/user/list", queryData);
 export const removeUserTunnel = (params: any) => Network.post("/tunnel/user/remove", params);
 export const updateUserTunnel = (data: any) => Network.post("/tunnel/user/update", data);