feat(storefront): homepage, module gating, widget protocol, i18n fixes

Storefront homepage & module gating:
- CMS owns storefront GET / (slug="home" with 3-tier resolution)
- Catalog loses GET / (keeps /products only)
- Store root redirect (GET / → /store/dashboard or /store/login)
- Route gating: non-core modules return 404 when disabled for platform
- Seed store default homepages per platform

Widget protocol for customer dashboard:
- StorefrontDashboardCard contract in widgets.py
- Widget aggregator get_storefront_dashboard_cards()
- Orders and Loyalty module widget providers
- Dashboard template renders contributed cards (no module names)

Landing template module-agnostic:
- CTAs driven by storefront_nav (not hardcoded module names)
- Header actions check nav item IDs (not enabled_modules)
- Remove hardcoded "Add Product" sidebar button
- Remove all enabled_modules checks from storefront templates

i18n fixes:
- Title placeholder resolution ({{store_name}}) for store default pages
- Storefront nav label_keys prefixed with module code
- Add storefront.account.* keys to 6 modules (en/fr/de/lb)
- Header/footer CMS pages use get_translated_title(current_language)
- Footer labels use i18n keys instead of hardcoded English

Icon cleanup:
- Standardize on map-pin (remove location-marker alias)
- Replace all location-marker references across templates and docs

Docs:
- Storefront builder vision proposal (6 phases)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

app/modules/orders/templates/orders/storefront/order-detail.html

@@ -178,7 +178,7 @@
                     <!-- Shipping Address -->
                     <div class="bg-white dark:bg-gray-800 rounded-lg shadow border border-gray-200 dark:border-gray-700 p-6">
                         <h3 class="text-lg font-semibold text-gray-900 dark:text-white mb-4 flex items-center">
-                            <span class="h-5 w-5 mr-2 text-gray-400" x-html="$icon('location-marker', 'h-5 w-5')"></span>
+                            <span class="h-5 w-5 mr-2 text-gray-400" x-html="$icon('map-pin', 'h-5 w-5')"></span>
                             Shipping Address
                         </h3>
                         <div class="text-sm text-gray-600 dark:text-gray-300 space-y-1">
@@ -302,7 +302,7 @@
                            rel="noopener noreferrer"
                            class="mt-3 w-full inline-flex justify-center items-center px-4 py-2 border border-transparent rounded-md shadow-sm text-sm font-medium text-white transition-colors"
                            style="background-color: var(--color-primary)">
-                            <span class="h-4 w-4 mr-2" x-html="$icon('location-marker', 'h-4 w-4')"></span>
+                            <span class="h-4 w-4 mr-2" x-html="$icon('map-pin', 'h-4 w-4')"></span>
                             Track Package
                         </a>
                     </div>