feat(icons): split built-in sprite into per-icon SVG sources and add ticket icon

Move the 114 built-in sprite icons out of assets/js/runtime/svg-icon.js into
assets/icons/sprite/{key}.svg and generate svg-icon.js with
tools/build-svg-sprite.mjs. Add ticket-color and use it for the user center
ticket entry. Update sidebar contract tests for the creator card labels.

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'  => 'manual-service'"), 'sidebar icon should reuse the existing headset sprite');
+  assert.ok(sidebar.includes("'icon'  => 'ticket-color'"), 'sidebar icon should use the built-in ticket sprite');
   assert.ok(sidebar.includes("'tab'   => 'tickets'"), 'sidebar tab key missing');
 
   const helper = read('inc/helpers/aksrt-user-center.php');