feat: add Translation Management with approval workflow

- New Translations + TranslationTexts NocoDB tables (auto-created on restart)
- Full CRUD: list, create, update, delete, bulk-delete translations
- Translation texts per language (add/edit/delete inline)
- Review flow: submit-review generates public token link
- Public review page: shows source + all translations, approve/reject/revision
- Email notifications to approvers (registered users)
- Sidebar nav under Marketing category
- Bilingual i18n (80+ keys in en.json and ar.json)

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

client/src/components/Sidebar.jsx

@@ -26,6 +26,7 @@ const moduleGroups = [
       { to: '/artefacts', icon: Palette, labelKey: 'nav.artefacts' },
       { to: '/assets', icon: Image, labelKey: 'nav.assets', tutorial: 'assets' },
       { to: '/brands', icon: Tag, labelKey: 'nav.brands' },
+      { to: '/translations', icon: Languages, labelKey: 'nav.translations' },
     ],
   },
   {