feat: add vue-i18n infrastructure and externalize all UI strings (A11Y-03)

Set up vue-i18n with English locale file containing 500+ keys organized
by view namespace. All 15 views converted to use t() calls instead of
hardcoded strings. Infrastructure ready for community translations.

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

neode-ui/package.json

@@ -28,26 +28,29 @@
     "fuse.js": "^7.1.0",
     "pinia": "^3.0.4",
     "vue": "^3.5.24",
+    "vue-i18n": "^11.3.0",
     "vue-router": "^4.6.3"
   },
   "devDependencies": {
+    "@playwright/test": "^1.58.2",
     "@types/node": "^24.10.0",
-    "@vue/test-utils": "^2.4.6",
-    "jsdom": "^25.0.1",
-    "vitest": "^3.1.1",
     "@vite-pwa/assets-generator": "^1.0.2",
     "@vitejs/plugin-vue": "^6.0.1",
+    "@vitest/coverage-v8": "^3.2.4",
+    "@vue/test-utils": "^2.4.6",
     "@vue/tsconfig": "^0.8.1",
     "autoprefixer": "^10.4.22",
     "concurrently": "^9.1.2",
     "cookie-parser": "^1.4.7",
     "cors": "^2.8.5",
     "express": "^4.21.2",
+    "jsdom": "^25.0.1",
     "postcss": "^8.5.6",
     "tailwindcss": "^3.4.18",
     "typescript": "~5.9.3",
     "vite": "^7.2.2",
     "vite-plugin-pwa": "^1.2.0",
+    "vitest": "^3.1.1",
     "vue-tsc": "^3.1.3",
     "ws": "^8.18.0"
   }