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

storefront/src/app/renter/saved-companies/page.tsx

@@ -4,11 +4,11 @@ import { useEffect, useState } from 'react'
 import Link from 'next/link'
 import { useRouter } from 'next/navigation'
 import { RenterAuthError, loadRenterProfile, type SavedCompany } from '@/lib/renter'
-import { useMarketplacePreferences } from '@/components/MarketplaceShell'
+import { useStorefrontPreferences } from '@/components/StorefrontShell'
 
 export default function RenterSavedCompaniesPage() {
   const router = useRouter()
-  const { language } = useMarketplacePreferences()
+  const { language } = useStorefrontPreferences()
   const dict = {
     en: {
       load: 'Could not load saved companies.',
@@ -17,7 +17,7 @@ export default function RenterSavedCompaniesPage() {
       back: 'Back to dashboard',
       loading: 'Loading saved companies…',
       empty: 'You have not saved any companies yet.',
-      browse: 'Browse the marketplace',
+      browse: 'Browse the storefront',
       rentalCompany: 'Rental company',
     },
     fr: {
@@ -27,7 +27,7 @@ export default function RenterSavedCompaniesPage() {
       back: 'Retour au tableau de bord',
       loading: 'Chargement des entreprises sauvegardées…',
       empty: 'Vous n’avez encore enregistré aucune entreprise.',
-      browse: 'Parcourir la marketplace',
+      browse: 'Parcourir la storefront',
       rentalCompany: 'Société de location',
     },
     ar: {