用户中心侧栏工单中心图标改用 comment-color

- sidebar-nav: 工单中心 icon ticket-color -> comment-color
- 删除 assets/icons/sprite/ticket-color.svg 并重建 svg-icon.js
- 同步更新相关契约测试

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

tests/widget-system/ticket-schema-contract.test.cjs

@@ -155,7 +155,7 @@ test('ticket panel is registered across the user-center wiring', () => {
 
   const sidebar = read('inc/helpers/user-center-renderers/sidebar-nav.php');
   assert.ok(sidebar.includes("'label' => __('工单中心', 'aksrt')"), 'sidebar label missing');
-  assert.ok(sidebar.includes("'icon'  => 'ticket-color'"), 'sidebar icon should use the built-in ticket sprite');
+  assert.ok(sidebar.includes("'icon'  => 'comment-color'"), 'sidebar icon should use the built-in comment sprite');
   assert.ok(sidebar.includes("'tab'   => 'tickets'"), 'sidebar tab key missing');
 
   const helper = read('inc/helpers/aksrt-user-center.php');