test(web): add middleware + i18n + messages test suites (GOO-60)

Cover frontend middleware auth/locale logic, i18n config/routing/request/navigation,
and vi/en message parity — 91 new tests across 6 files.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

apps/web/package.json

@@ -8,6 +8,7 @@
     "start": "next start",
     "lint": "eslint src/ app/ components/ lib/ hooks/ i18n/ --no-error-on-unmatched-pattern",
     "test": "vitest run",
+    "test:coverage": "vitest run --coverage",
     "typecheck": "tsc --noEmit"
   },
   "dependencies": {
@@ -44,6 +45,7 @@
     "@types/react": "^18.3.0",
     "@types/react-dom": "^18.3.0",
     "@vitejs/plugin-react": "^4.7.0",
+    "@vitest/coverage-v8": "^4.1.3",
     "autoprefixer": "^10.4.0",
     "jsdom": "^29.0.2",
     "msw": "^2.13.2",