feat(web): заготовка веб-клиента на Vite + React 19 + TypeScript strict

- стек по §5.2: React 19, React Router, TanStack Query, Zustand, Tailwind CSS 4,
  i18next (ru/en), Vitest + Testing Library
- дизайн-токены §3 docs/client-web.md (тёмная тема по умолчанию, светлая, accent)
- типизированный API-клиент §8.1: единый формат ошибок, ApiError с кодом
- App: экран состояния фундамента с readz/meta, локализация ошибок по code
- тесты: клиент API, форматирование, рендер App (успех/ошибка кода/сеть)
- eslint + prettier + tsc strict; initial JS 97.6 KB gzip

web/src/i18n/locales/en.json

@@ -0,0 +1,44 @@
+{
+  "app": {
+    "name": "glchat",
+    "tagline": "Self-hosted communication: text, voice, video"
+  },
+  "status": {
+    "title": "Foundation deployed",
+    "description": "The server responds, the database runs in WAL mode, migrations are applied. Chat features arrive in the next phases.",
+    "connecting": "Checking server status…",
+    "instance": "Instance",
+    "version": "Version",
+    "apiVersion": "API version",
+    "schemaReady": "Database",
+    "schemaOk": "ready",
+    "maxUpload": "Maximum upload size",
+    "checks": "Checks",
+    "retry": "Retry"
+  },
+  "health": {
+    "online": "Server is reachable",
+    "offline": "Server is unreachable"
+  },
+  "errors": {
+    "network.unreachable": "The server is not responding. Check your connection and try again.",
+    "network.aborted": "The request was aborted.",
+    "instance.not_ready": "The instance is still starting. Try again in a few seconds.",
+    "internal.error": "Internal server error.",
+    "not_found": "The requested resource was not found.",
+    "unknown": "Unknown error ({{code}})."
+  },
+  "theme": {
+    "switchToLight": "Light theme",
+    "switchToDark": "Dark theme"
+  },
+  "language": {
+    "label": "Language",
+    "ru": "Русский",
+    "en": "English"
+  },
+  "footer": {
+    "source": "Source code",
+    "license": "AGPL-3.0"
+  }
+}