fix: use fr-LU locale for currency formatting (29,99 €)

Update all shop templates to use French Luxembourg locale which
displays the Euro sign after the number: 29,99 €

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

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

app/templates/shop/account/orders.html

@@ -219,7 +219,7 @@ function shopOrdersPage() {
 
         formatPrice(amount) {
             if (!amount && amount !== 0) return '-';
-            return new Intl.NumberFormat('de-DE', {
+            return new Intl.NumberFormat('fr-LU', {
                 style: 'currency',
                 currency: 'EUR'
             }).format(amount);