refactor(admin): 去掉 two_factor_auth 残留

后端已删除该 model 字段，2FA 功能整体移除。

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

src/admin/user/list.vue

@@ -172,7 +172,6 @@ function createNewUser() {
     problem_permission: "None",
     create_time: new Date(),
     last_login: new Date(),
-    two_factor_auth: false,
     open_api: false,
     is_disabled: false,
     password: "",

src/utils/types.ts

@@ -35,7 +35,6 @@ export interface User {
   problem_permission: string
   create_time: Date
   last_login: Date
-  two_factor_auth: boolean
   open_api: boolean
   is_disabled: boolean
   password?: string