feat: i18n — EN/MS/ZH translations with cookie-based locale switching, report form translated

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FFDuBhMKvoWjrWT3ZnGmmr

tests/lib/i18n/translations.test.ts

@@ -0,0 +1,30 @@
+import { describe, it, expect } from 'vitest'
+import en from '@/messages/en.json'
+import ms from '@/messages/ms.json'
+import zh from '@/messages/zh.json'
+
+const NAMESPACES = ['ReportForm', 'IncidentType', 'MedicalStatus'] as const
+
+NAMESPACES.forEach(ns => {
+  describe(`${ns} namespace`, () => {
+    const enKeys = Object.keys(en[ns])
+
+    it(`ms.${ns} has all keys present in en.${ns}`, () => {
+      const msKeys = Object.keys(ms[ns])
+      enKeys.forEach(key => expect(msKeys, `missing key: ${key}`).toContain(key))
+    })
+
+    it(`zh.${ns} has all keys present in en.${ns}`, () => {
+      const zhKeys = Object.keys(zh[ns])
+      enKeys.forEach(key => expect(zhKeys, `missing key: ${key}`).toContain(key))
+    })
+
+    it(`en.${ns} values are non-empty strings`, () => {
+      enKeys.forEach(key => {
+        const val = (en[ns] as Record<string, string>)[key]
+        expect(typeof val).toBe('string')
+        expect(val.length).toBeGreaterThan(0)
+      })
+    })
+  })
+})