chore: wire Carplace into dev and production stacks

apps/carplace/src/lib/i18n.server.test.ts

@@ -0,0 +1,30 @@
+import { beforeEach, describe, expect, it, vi } from 'vitest'
+
+const cookieValues = vi.hoisted(() => new Map<string, string>())
+
+vi.mock('next/headers', () => ({
+  cookies: async () => ({
+    get: (name: string) => {
+      const value = cookieValues.get(name)
+      return value === undefined ? undefined : { value }
+    },
+  }),
+}))
+
+import { getCarplaceLanguage } from './i18n.server'
+import { SHARED_LANGUAGE_COOKIE } from './i18n'
+
+describe('getCarplaceLanguage', () => {
+  beforeEach(() => cookieValues.clear())
+
+  it.each(['en', 'fr', 'ar'] as const)('reads the shared %s language cookie', async (language) => {
+    cookieValues.set(SHARED_LANGUAGE_COOKIE, language)
+    await expect(getCarplaceLanguage()).resolves.toBe(language)
+  })
+
+  it('defaults to English when the shared cookie is absent or invalid', async () => {
+    await expect(getCarplaceLanguage()).resolves.toBe('en')
+    cookieValues.set(SHARED_LANGUAGE_COOKIE, 'es')
+    await expect(getCarplaceLanguage()).resolves.toBe('en')
+  })
+})