feat(user-ban): frontend ban modal replaces the backend restrictions tab

1:1 replicate the reference theme user-ban flow on the frontend:

- Ban/unban modal rendered by inc/helpers/user-ban.php, opened via
  AksrtModalRuntime.openRemote (600px desktop dialog, 360px initial
  height, mobile bottom drawer, c-yellow colorful unban header).
- Three entry points wired: user homepage cover three-dot menu,
  comment section menu, article author card menu (ban item takes
  priority over report, matching the reference hook order).
- REST endpoints /user-ban/modal and /user-ban/set under aksrt/v1,
  guarded by check_permission, persisted through User\Restriction.
- Submit semantics match zib_ajax_set_user_ban: ban reloads the page,
  unban only closes the modal.

Cleanup (no dual-track): the backend ban-restrictions tab, its form
handlers and flash keys are removed; ticket processing links to the
frontend user homepage as the reference theme does; admin/report and
appeal notification URLs move to type/status query args.

Verification: 337/337 widget-system contract tests, 41/41 admin and
front-submit tests, php -l clean on all changed PHP files.

src/User/BanAppeal.php

@@ -141,7 +141,8 @@ class BanAppeal {
 					$summary,
 					[
 						'title'      => __('禁封申诉', 'aksrt'),
-						'target_url' => admin_url('users.php?page=aksrt_user_ban&tab=appeals'),
+						// 直达待处理申诉队列（与工单页 type=appeal&status=pending 过滤同参）。
+						'target_url' => admin_url('users.php?page=aksrt_user_ban&type=appeal&status=pending'),
 					]
 				);
 			}