refactor: rename marketplace to storefront across the entire monorepo

Comprehensive rename of all marketplace references to storefront:
- API module: apps/api/src/modules/marketplace/ → storefront/
- Components: MarketplaceHeader → StorefrontHeader, MarketplaceShell →
  StorefrontShell, MarketplaceFooter → StorefrontFooter
- Types: marketplace-homepage.ts → storefront-homepage.ts
- Test files: employee-marketplace-* → employee-storefront-*
- All source code identifiers, imports, route paths, and strings
- Documentation (docs/), CI config (.gitlab-ci.yml), scripts
- Dashboard, admin, storefront workspace references
- Prisma field names preserved (isListedOnMarketplace, marketplaceRating,
  marketplaceFunnelEvent) as they map to database schema

Validation:
- API type-check: 0 errors
- Storefront type-check: 0 errors
- Dashboard type-check: 0 errors
- Full monorepo type-check: only pre-existing admin TS18046

apps/dashboard/src/app/(dashboard)/offers/page.tsx

@@ -113,7 +113,7 @@ function offerToForm(o: Offer): FormState {
 const copy = {
   en: {
     title: 'Offers',
-    subtitle: 'Promotions shown on your site and optionally on the marketplace.',
+    subtitle: 'Promotions shown on your site and optionally on the storefront.',
     createOffer: 'Create Offer',
     editOffer: 'Edit Offer',
     deleteOffer: 'Delete Offer',
@@ -126,7 +126,7 @@ const copy = {
     ends: 'ends',
     active: 'Active',
     inactive: 'Inactive',
-    marketplace: 'Marketplace',
+    storefront: 'Storefront',
     featured: 'Featured',
     empty: 'No offers yet. Create your first offer to attract customers.',
     labelTitle: 'Title *',
@@ -146,7 +146,7 @@ const copy = {
     labelValidFrom: 'Valid From *',
     labelValidUntil: 'Valid Until *',
     labelIsActive: 'Active',
-    labelIsPublic: 'Show on marketplace',
+    labelIsPublic: 'Show on storefront',
     labelIsFeatured: 'Featured',
     typePERCENTAGE: 'Percentage (%)',
     typeFIXED_AMOUNT: 'Fixed Amount (MAD)',
@@ -174,7 +174,7 @@ const copy = {
   },
   fr: {
     title: 'Offres',
-    subtitle: 'Promotions affichées sur votre site et éventuellement sur la marketplace.',
+    subtitle: 'Promotions affichées sur votre site et éventuellement sur la storefront.',
     createOffer: 'Créer une offre',
     editOffer: "Modifier l'offre",
     deleteOffer: "Supprimer l'offre",
@@ -187,7 +187,7 @@ const copy = {
     ends: 'expire le',
     active: 'Actif',
     inactive: 'Inactif',
-    marketplace: 'Marketplace',
+    storefront: 'Storefront',
     featured: 'Mise en avant',
     empty: 'Aucune offre. Créez votre première offre pour attirer des clients.',
     labelTitle: 'Titre *',
@@ -207,7 +207,7 @@ const copy = {
     labelValidFrom: 'Valable du *',
     labelValidUntil: "Valable jusqu'au *",
     labelIsActive: 'Actif',
-    labelIsPublic: 'Afficher sur la marketplace',
+    labelIsPublic: 'Afficher sur la storefront',
     labelIsFeatured: 'Mise en avant',
     typePERCENTAGE: 'Pourcentage (%)',
     typeFIXED_AMOUNT: 'Montant fixe (MAD)',
@@ -248,7 +248,7 @@ const copy = {
     ends: 'تنتهي في',
     active: 'نشط',
     inactive: 'غير نشط',
-    marketplace: 'السوق',
+    storefront: 'السوق',
     featured: 'مميز',
     empty: 'لا توجد عروض بعد. أنشئ أول عرض لجذب العملاء.',
     labelTitle: 'العنوان *',
@@ -514,7 +514,7 @@ export default function OffersPage() {
             )}
 
             <div className="flex flex-wrap gap-2">
-              {offer.isPublic && <span className="badge-blue">{t.marketplace}</span>}
+              {offer.isPublic && <span className="badge-blue">{t.storefront}</span>}
               {offer.isFeatured && <span className="badge-purple">{t.featured}</span>}
               {offer.promoCode && <span className="badge-amber">{offer.promoCode}</span>}
               {typeof offer.redemptionCount === 'number' && (