feat(admin): redesign VIP membership page with modal editing

- Replace per-row inline <details> forms and the separate bulk form with a
  single <dialog> shared by single-user and bulk adjustments
- Add stats row, styled tabs, date range filter with reset, sortable expiry
- Show fallback tier, remaining time, and disable unavailable operations
- History tab: labelled operation/status badges, avatars, local time,
  batch marker and error message
- Move inline script/onclick to assets/js/admin-vip.js; add vip.css
- Surface the service error message when every user fails

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

src/Admin/Native/UsersMenus.php

@@ -46,6 +46,7 @@ class UsersMenus {
         add_action('admin_enqueue_scripts', [$this, 'enqueue_ticket_assets']);
         add_action('admin_enqueue_scripts', [$this, 'enqueue_message_assets']);
         add_action('admin_enqueue_scripts', [$this, 'enqueue_invite_assets']);
+        add_action('admin_enqueue_scripts', [$this, 'enqueue_vip_assets']);
     }
 
     public function register_menus(): void {