feat: add configurable currency locale and fix vendor JS init

Currency Locale Configuration:
- Add platform-level storefront settings (locale, currency)
- Create PlatformSettingsService with resolution chain:
  vendor → AdminSetting → environment → hardcoded fallback
- Add storefront_locale nullable field to Vendor model
- Update shop routes to resolve and pass locale to templates
- Add window.SHOP_CONFIG for frontend JavaScript access
- Centralize formatPrice() in shop-layout.js using SHOP_CONFIG
- Remove local formatPrice functions from shop templates

Vendor JS Bug Fix:
- Fix vendorCode being null on all vendor pages
- Root cause: page components overriding init() without calling parent
- Add parent init call to 14 vendor JS files
- Add JS-013 architecture rule to prevent future regressions
- Validator now checks vendor JS files for parent init pattern

Files changed:
- New: app/services/platform_settings_service.py
- New: alembic/versions/s7a8b9c0d1e2_add_storefront_locale_to_vendors.py
- Modified: 14 vendor JS files, shop templates, validation scripts

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

app/templates/shop/account/order-detail.html

@@ -462,13 +462,7 @@ function shopOrderDetailPage() {
             return this.statuses[status]?.class || 'bg-gray-100 text-gray-800 dark:bg-gray-700 dark:text-gray-200';
         },
 
-        formatPrice(amount) {
-            if (!amount && amount !== 0) return '-';
-            return new Intl.NumberFormat('fr-LU', {
-                style: 'currency',
-                currency: 'EUR'
-            }).format(amount);
-        },
+        // formatPrice is inherited from shopLayoutData() via spread operator
 
         formatDateTime(dateStr) {
             if (!dateStr) return '-';

app/templates/shop/account/orders.html

@@ -217,13 +217,7 @@ function shopOrdersPage() {
             return this.statuses[status]?.class || 'bg-gray-100 text-gray-800 dark:bg-gray-700 dark:text-gray-200';
         },
 
-        formatPrice(amount) {
-            if (!amount && amount !== 0) return '-';
-            return new Intl.NumberFormat('fr-LU', {
-                style: 'currency',
-                currency: 'EUR'
-            }).format(amount);
-        },
+        // formatPrice is inherited from shopLayoutData() via spread operator
 
         formatDate(dateStr) {
             if (!dateStr) return '-';

app/templates/shop/account/profile.html

@@ -523,13 +523,7 @@ function shopProfilePage() {
             }
         },
 
-        formatPrice(amount) {
-            if (!amount && amount !== 0) return '-';
-            return new Intl.NumberFormat('fr-LU', {
-                style: 'currency',
-                currency: 'EUR'
-            }).format(amount);
-        },
+        // formatPrice is inherited from shopLayoutData() via spread operator
 
         formatDate(dateStr) {
             if (!dateStr) return '-';

app/templates/shop/base.html

@@ -308,19 +308,28 @@
     {# 1. Log Configuration (must load first) #}
     <script src="{{ url_for('static', path='shared/js/log-config.js') }}"></script>
 
-    {# 2. Icon System #}
+    {# 2. Global Shop Configuration (currency/locale settings) #}
+    <script>
+        window.SHOP_CONFIG = {
+            locale: '{{ storefront_locale | default("fr-LU") }}',
+            currency: '{{ storefront_currency | default("EUR") }}',
+            language: '{{ request.state.language|default("fr") }}'
+        };
+    </script>
+
+    {# 3. Icon System #}
     <script src="{{ url_for('static', path='shared/js/icons.js') }}"></script>
 
-    {# 3. Base Shop Layout (Alpine.js component - must load before Alpine) #}
+    {# 4. Base Shop Layout (Alpine.js component - must load before Alpine) #}
     <script src="{{ url_for('static', path='shop/js/shop-layout.js') }}"></script>
 
-    {# 4. Utilities #}
+    {# 5. Utilities #}
     <script src="{{ url_for('static', path='shared/js/utils.js') }}"></script>
 
-    {# 5. API Client #}
+    {# 6. API Client #}
     <script src="{{ url_for('static', path='shared/js/api-client.js') }}"></script>
 
-    {# 6. Alpine.js with CDN fallback (deferred - loads last) #}
+    {# 7. Alpine.js with CDN fallback (deferred - loads last) #}
     <script>
     (function() {
         var script = document.createElement('script');
@@ -339,7 +348,7 @@
     })();
     </script>
 
-    {# 7. Page-specific JavaScript #}
+    {# 8. Page-specific JavaScript #}
     {% block extra_scripts %}{% endblock %}
 
     {# Toast notification container #}

app/templates/shop/products.html

@@ -207,13 +207,7 @@ document.addEventListener('alpine:init', () => {
             this.loadProducts();
         },
 
-        formatPrice(amount) {
-            if (!amount && amount !== 0) return '';
-            return new Intl.NumberFormat('fr-LU', {
-                style: 'currency',
-                currency: 'EUR'
-            }).format(amount);
-        },
+        // formatPrice is inherited from shopLayoutData() via spread operator
 
         async addToCart(product) {
             console.log('[SHOP] Adding to cart:', product);