feat(user-center): promote invite into standalone 推广中心 tab

Register a dedicated `promotion` dashboard panel gated by the existing
invite switches (credits + invite reward + invite registration), and move
the invite card out of the revenue tab so 收益中心 is pure earnings/withdrawal.

- src/User/Center.php: register promotion panel; revenue no longer depends
  on invite being on
- inc/helpers/user-center-renderers/profile-promotion.php: new panel body
  hosting the existing [data-aksrt-invite] card
- profile-revenue.php: drop the invite section; aksrt-user-center.php: drop
  unused show_invite_section context, add promotion to built-in tabs + view map
- repoint invite/promotion deep-link aliases from revenue to promotion across
  tab-url builder, tab resolver, runtime tabAliases, urls.php, and the
  revenue-JS enqueue gate
- sidebar-nav.php: add 推广中心 service entry; shell.css: entry icon color;
  sidebar-creator.php: reword revenue card
- UserRuntime.php: allow promotion in configurable tabs

src/Settings/UserRuntime.php

@@ -90,7 +90,7 @@ class UserRuntime {
 
         // Built-in switchable panels. VIP is always auto-injected when enabled
         // by AKSRT\User\Center — keep it allowed for explicit config too.
-        $allowed_tabs = ['profile', 'level', 'posts', 'comments', 'favorites', 'credits', 'revenue', 'vip', 'orders', 'auth', 'settings'];
+        $allowed_tabs = ['profile', 'level', 'posts', 'comments', 'favorites', 'credits', 'promotion', 'revenue', 'vip', 'orders', 'auth', 'settings'];
         $normalized_tabs = ['profile'];
 
         foreach ((array) $tabs as $tab) {