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/dashboard/page.tsx

@@ -3,7 +3,7 @@
 import { useEffect, useState } from 'react'
 import Link from 'next/link'
 import { useRouter } from 'next/navigation'
-import { useMarketplacePreferences } from '@/components/MarketplaceShell'
+import { useStorefrontPreferences } from '@/components/StorefrontShell'
 
 const API_BASE = process.env.NEXT_PUBLIC_API_URL ?? 'http://localhost:4000/api/v1'
 
@@ -29,7 +29,7 @@ type Status = 'loading' | 'ready' | 'error'
 
 export default function RenterDashboardPage() {
   const router = useRouter()
-  const { language } = useMarketplacePreferences()
+  const { language } = useStorefrontPreferences()
   const dict = {
     en: {
       loadProfile: 'Could not load profile.',
@@ -52,7 +52,7 @@ export default function RenterDashboardPage() {
       savedCompanies: 'Saved companies',
       noneSaved: 'None saved yet',
       saved: 'saved',
-      saveCompaniesPrompt: 'Save companies you like while browsing the marketplace.',
+      saveCompaniesPrompt: 'Save companies you like while browsing the storefront.',
       startExploring: 'Start exploring',
       rentalCompany: 'Rental company',
     },
@@ -77,7 +77,7 @@ export default function RenterDashboardPage() {
       savedCompanies: 'Entreprises sauvegardées',
       noneSaved: 'Aucune pour le moment',
       saved: 'sauvegardées',
-      saveCompaniesPrompt: 'Enregistrez les entreprises que vous aimez en parcourant la marketplace.',
+      saveCompaniesPrompt: 'Enregistrez les entreprises que vous aimez en parcourant la storefront.',
       startExploring: 'Commencer à explorer',
       rentalCompany: 'Société de location',
     },