fix(navigation): align mega-menu rendering and menu-item backend with the reference

Renderer:
- Graphic-card images carry fit-cover so they crop into the fixed card box
  instead of stretching it and pushing the title out of alignment.
- Mega-menu link icons use fa-fw (fixed glyph column) instead of the
  undefined menu-item-icon class, so link titles line up.

Backend:
- Restore show_policy (login / vip / vip_2 / auth) on menu items; the field
  was missing entirely, so items could not be gated by identity.
- Default submenu_type to graphic_card, badge_class to jb-red, arrangement
  to swiper, size to md.
- Clamp img_scale to 20-300 to match the reference's spinner bounds.
- Drop the now-meaningless "none" submenu_type option: the senior-submenu
  switch is itself the on/off control.
- Admin JS gains the align control (left/center/space-around).

Cleanup:
- Remove the unused header_actions nav menu location.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

src/Core/Setup.php

@@ -78,11 +78,10 @@ class Setup {
 
     public function register_nav_menus(): void {
         register_nav_menus([
-            'primary'        => __('主导航', 'jio'),
-            'mobile'         => __('移动端菜单', 'jio'),
-            'footer'         => __('页脚菜单', 'jio'),
-            'social'         => __('社交链接', 'jio'),
-            'header_actions' => __('顶部右侧入口', 'jio'),
+            'primary' => __('主导航', 'jio'),
+            'mobile'  => __('移动端菜单', 'jio'),
+            'footer'  => __('页脚菜单', 'jio'),
+            'social'  => __('社交链接', 'jio'),
         ]);
     }