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/Settings/MailNotifications.php

@@ -147,7 +147,7 @@ final class MailNotifications {
 
     public static function ban_appeal_submitted(int $user_id, array $payload): void {
         $user = get_userdata($user_id);
-        if ($user instanceof \WP_User) self::send_admin('ban_appeal_admin', ['username' => $user->display_name, 'url' => admin_url('users.php?page=aksrt_user_ban&tab=appeals')]);
+        if ($user instanceof \WP_User) self::send_admin('ban_appeal_admin', ['username' => $user->display_name, 'url' => admin_url('users.php?page=aksrt_user_ban&type=appeal&status=pending')]);
     }
 
     public static function ban_appeal_processed(int $user_id, string $decision, string $note): void {