feat(i18n): add language switcher

tests/unit/i18n/dictionaries.test.ts

@@ -26,6 +26,24 @@ describe("i18n dictionaries", () => {
     })
   })
 
+  it("provides localized language switcher copy for English and Spanish", () => {
+    expect(getDictionary("en").common.languageSwitcher).toEqual({
+      label: "Language",
+      options: {
+        en: "English",
+        es: "Spanish",
+      },
+    })
+
+    expect(getDictionary("es").common.languageSwitcher).toEqual({
+      label: "Idioma",
+      options: {
+        en: "Inglés",
+        es: "Español",
+      },
+    })
+  })
+
   it("keeps dashboard home dictionary keys aligned across locales", () => {
     expect(getDictionary("en").dashboardHome).toEqual({
       heading: "Dashboard",

tests/unit/i18n/locales.test.ts

@@ -4,6 +4,7 @@ import {
   DEFAULT_LOCALE_ENV_VAR,
   FALLBACK_LOCALE,
   isLocale,
+  LOCALE_COOKIE_MAX_AGE_SECONDS,
   LOCALE_COOKIE_NAME,
   resolveDefaultLocale,
   resolveLocale,
@@ -16,6 +17,7 @@ describe("i18n locales", () => {
     expect(FALLBACK_LOCALE).toBe("en")
     expect(DEFAULT_LOCALE_ENV_VAR).toBe("STOCK_MANAGER_DEFAULT_LOCALE")
     expect(LOCALE_COOKIE_NAME).toBe("stock-manager-locale")
+    expect(LOCALE_COOKIE_MAX_AGE_SECONDS).toBe(60 * 60 * 24 * 365)
   })
 
   it("accepts only exact supported locale codes", () => {