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

docs/project-design/COOKIE_POLICY.md

@@ -52,7 +52,7 @@ We do not use analytics cookies, advertising cookies, or third-party tracking co
 | **Scope** | All pages (`path=/`) |
 | **Third-party** | No |
 
-**Purpose:** Stores your chosen display language so the interface appears in your preferred language on every visit across all parts of the platform (public marketplace, dashboard, and admin panel). Supported values are English (`en`), French (`fr`), and Arabic (`ar`).
+**Purpose:** Stores your chosen display language so the interface appears in your preferred language on every visit across all parts of the platform (public storefront, dashboard, and admin panel). Supported values are English (`en`), French (`fr`), and Arabic (`ar`).
 
 **When it is set:** When you change the language using the language selector, or automatically on first visit based on your browser's language settings.  
 **Can you opt out?** You can block this cookie. If you do, the platform will fall back to a default language and you may need to select your language on every visit.
@@ -97,7 +97,7 @@ We do not use analytics cookies, advertising cookies, or third-party tracking co
 
 | Field | Value |
 |---|---|
-| **Names** | `dashboard-language`, `marketplace-language` |
+| **Names** | `dashboard-language`, `storefront-language` |
 | **Category** | Functional / preference |
 | **Duration** | 1 year |
 | **Scope** | All pages (`path=/`) |