feat(admin): list-modal UI for header icon cards repeater

Render icon cards as a compact list with edit/delete actions and
preview on the right; field data is edited in a modal. Opt-in via
schema ui=list-modal so other repeaters stay inline.

assets/admin/src/schema/sections/page-display/index.js

@@ -712,6 +712,17 @@ export const pageDisplaySchemas = {
             key: 'header_components_icon_cards',
             label: '图标卡片',
             type: 'repeater',
+            ui: 'list-modal',
+            listPreview: {
+              iconKey: 'icon',
+              customIconKey: 'custom_icon',
+              iconClassKey: 'icon_class',
+              titleKey: 'title',
+              descKey: 'desc',
+              urlKey: 'url',
+            },
+            editText: '编辑卡片',
+            emptyText: '暂无图标卡片',
             sanitize_type: 'array',
             default: [],
             dependsOn: { key: 'header_components_cards_enabled', value: true },