feat(admin): separate platform CRUD from CMS, add entity selector macro

- Move platforms menu from CMS to Platform Admin section with create/edit
- Add platform create page, API endpoint, and service method
- Remove CMS-specific content from platform list and detail pages
- Create shared entity_selector + entity_selected_badge Jinja macros
- Create entity-selector.js generalizing store-selector.js for any entity
- Add Tom Select merchant filter to stores page with localStorage persistence
- Migrate store-products page to use shared macros (remove 53 lines of duped CSS)
- Fix broken icons: puzzle→puzzle-piece, building-storefront→store, language→translate, server→cube

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/modules/tenancy/static/admin/js/platform-detail.js

@@ -17,7 +17,6 @@ function platformDetail() {
     // State
     platform: null,
     stats: null,
-    recentPages: [],
     loading: true,
     error: null,
     platformCode: null,
@@ -41,10 +40,7 @@ function platformDetail() {
         if (match) {
           this.platformCode = match[1];
           platformDetailLog.info('Viewing platform:', this.platformCode);
-          await Promise.all([
-            this.loadPlatform(),
-            this.loadRecentPages(),
-          ]);
+          await this.loadPlatform();
         } else {
           platformDetailLog.error('No platform code in URL');
           this.error = 'Platform code not found in URL';
@@ -74,19 +70,6 @@ function platformDetail() {
       }
     },
 
-    async loadRecentPages() {
-      try {
-        // Load recent content pages for this platform
-        const response = await apiClient.get(`/admin/content-pages?platform_code=${this.platformCode}&limit=5`);
-        this.recentPages = response.items || response || [];
-        platformDetailLog.info(`Loaded ${this.recentPages.length} recent pages`);
-      } catch (err) {
-        platformDetailLog.error('Error loading recent pages:', err);
-        // Non-fatal - don't throw
-        this.recentPages = [];
-      }
-    },
-
     // Helper Methods
     getPlatformIcon(code) {
       const icons = {
@@ -98,22 +81,6 @@ function platformDetail() {
       return icons[code] || 'globe-alt';
     },
 
-    getPageTypeLabel(page) {
-      if (page.is_platform_page) return 'Marketing';
-      if (page.store_id) return 'Store Override';
-      return 'Store Default';
-    },
-
-    getPageTypeBadgeClass(page) {
-      if (page.is_platform_page) {
-        return 'bg-purple-100 text-purple-800 dark:bg-purple-900 dark:text-purple-200';
-      }
-      if (page.store_id) {
-        return 'bg-teal-100 text-teal-800 dark:bg-teal-900 dark:text-teal-200';
-      }
-      return 'bg-blue-100 text-blue-800 dark:bg-blue-900 dark:text-blue-200';
-    },
-
     formatDate(dateString) {
       if (!dateString) return '—';
       const date = new Date(dateString);