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/lib/api.test.ts

@@ -1,5 +1,5 @@
 import { afterEach, describe, expect, it, vi } from 'vitest'
-import { MarketplaceApiError, marketplaceFetch, marketplaceFetchOrDefault, marketplacePost } from './api'
+import { StorefrontApiError, storefrontFetch, storefrontFetchOrDefault, storefrontPost } from './api'
 
 afterEach(() => {
   delete process.env.NEXT_PUBLIC_API_URL
@@ -8,19 +8,19 @@ afterEach(() => {
   Reflect.deleteProperty(globalThis, 'fetch')
 })
 
-describe('marketplace API helpers', () => {
+describe('storefront API helpers', () => {
   it('unwraps successful GET responses from the data envelope', async () => {
     const fetchMock = vi.fn(async () => ({ ok: true, json: async () => ({ data: [{ id: 'vehicle_1' }] }) }))
     Object.defineProperty(globalThis, 'fetch', { configurable: true, value: fetchMock })
 
-    await expect(marketplaceFetch('/marketplace/vehicles')).resolves.toEqual([{ id: 'vehicle_1' }])
-    expect(fetchMock).toHaveBeenCalledWith(expect.stringMatching(/\/api\/v1\/marketplace\/vehicles$/), {
+    await expect(storefrontFetch('/storefront/vehicles')).resolves.toEqual([{ id: 'vehicle_1' }])
+    expect(fetchMock).toHaveBeenCalledWith(expect.stringMatching(/\/api\/v1\/storefront\/vehicles$/), {
       cache: 'no-store',
       credentials: 'include',
     })
   })
 
-  it('throws rich marketplace API errors', async () => {
+  it('throws rich storefront API errors', async () => {
     Object.defineProperty(globalThis, 'fetch', {
       configurable: true,
       value: vi.fn(async () => ({
@@ -30,8 +30,8 @@ describe('marketplace API helpers', () => {
       })),
     })
 
-    await expect(marketplaceFetch('/marketplace/book')).rejects.toMatchObject({
-      name: 'MarketplaceApiError',
+    await expect(storefrontFetch('/storefront/book')).rejects.toMatchObject({
+      name: 'StorefrontApiError',
       message: 'Vehicle unavailable',
       status: 409,
       code: 'VEHICLE_UNAVAILABLE',
@@ -45,7 +45,7 @@ describe('marketplace API helpers', () => {
       value: vi.fn(async () => ({ ok: false, status: 500, json: async () => ({ message: 'Down' }) })),
     })
 
-    await expect(marketplaceFetchOrDefault('/marketplace/homepage', { hero: null })).resolves.toEqual({ hero: null })
+    await expect(storefrontFetchOrDefault('/storefront/homepage', { hero: null })).resolves.toEqual({ hero: null })
   })
 
   it('posts JSON payloads and unwraps successful responses', async () => {
@@ -53,7 +53,7 @@ describe('marketplace API helpers', () => {
     const fetchMock = vi.fn(async () => ({ ok: true, json: async () => ({ data: { id: 'reservation_1' } }) }))
     Object.defineProperty(globalThis, 'fetch', { configurable: true, value: fetchMock })
 
-    await expect(marketplacePost('/site/reservations', { vehicleId: 'vehicle_1' })).resolves.toEqual({ id: 'reservation_1' })
+    await expect(storefrontPost('/site/reservations', { vehicleId: 'vehicle_1' })).resolves.toEqual({ id: 'reservation_1' })
     expect(fetchMock).toHaveBeenCalledWith('https://api.example.com/api/v1/site/reservations', expect.objectContaining({
       method: 'POST',
       credentials: 'include',
@@ -68,8 +68,8 @@ describe('marketplace API helpers', () => {
       value: vi.fn(async () => ({ ok: false, status: 502, json: async () => { throw new Error('bad json') } })),
     })
 
-    await expect(marketplaceFetch('/site/homepage')).rejects.toMatchObject({
-      name: 'MarketplaceApiError',
+    await expect(storefrontFetch('/site/homepage')).rejects.toMatchObject({
+      name: 'StorefrontApiError',
       message: 'Request failed',
       status: 502,
     })