refactor: complete JS i18n migration for confirm dialogs and toast messages

Migrate 34 hardcoded user-facing strings to use I18n.t() for translation:

- CMS: media file operations (5 strings)
- Marketplace: Letzshop integration (16 strings)
- Messaging: notifications, messages, email templates (5 strings)
- Tenancy: platform modules, menu config, theme (5 strings)
- Core: menu config, settings, storefront cart (5 strings)
- Catalog: product creation (3 strings)
- Utils: clipboard operations (2 strings)

Added confirmations and messages keys to module locale files.
Added I18n.loadModule() calls to JS files that were missing them.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

static/shared/js/utils.js

@@ -140,10 +140,13 @@ const Utils = {
     async copyToClipboard(text) {
         try {
             await navigator.clipboard.writeText(text);
-            this.showToast('Copied to clipboard', 'success');
+            // Use I18n if available, fallback to hardcoded string
+            const message = typeof I18n !== 'undefined' ? I18n.t('clipboard.copied') : 'Copied to clipboard';
+            this.showToast(message, 'success');
         } catch (error) {
             console.error('Failed to copy:', error);
-            this.showToast('Failed to copy', 'error');
+            const message = typeof I18n !== 'undefined' ? I18n.t('clipboard.failed') : 'Failed to copy';
+            this.showToast(message, 'error');
         }
     },