feat(web): sign-in, first-run setup, app shell and user admin (M1)

- core: AuthSession keeps the access token in memory, refreshes it
  once for all parallel requests (single-flight) and retries them;
  refresh races between tabs are retried, reuse signs out; ApiError
  carries problem+json codes and field errors
- web: TanStack Router with guards — guests go to /login, the bootstrap
  admin to /setup/admin, temporary passwords to /setup/password, admin
  pages by role
- login, setup screens, Classic shell (top bar, role-based sidebar,
  empty player), settings: name, theme, language, password, devices
- users admin: search, role filter, create with a one-time temporary
  password, reset, block, role change, delete as the policy allows;
  audit log for admins
- ru/en strings for auth, admin and error codes; language and theme
  are saved in the profile

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

packages/i18n/locales/ru/common.json

@@ -17,5 +17,67 @@
     "label": "Язык",
     "ru": "Русский",
     "en": "English"
+  },
+  "nav": {
+    "main": "Навигация",
+    "home": "Главная",
+    "admin": "Админка",
+    "users": "Пользователи",
+    "audit": "Журнал"
+  },
+  "profile": {
+    "menu": "Меню профиля",
+    "settings": "Настройки",
+    "logout": "Выйти"
+  },
+  "roles": {
+    "admin": "Администратор",
+    "moderator": "Модератор",
+    "user": "Пользователь"
+  },
+  "home": {
+    "greeting": "Привет, {{name}}!",
+    "wave": "Моя волна",
+    "wave_soon": "Бесконечная лента под ваш вкус появится, когда сервер подключит библиотеку."
+  },
+  "player": {
+    "empty": "Ничего не играет"
+  },
+  "settings": {
+    "title": "Настройки",
+    "account": "Аккаунт",
+    "display_name": "Отображаемое имя",
+    "save": "Сохранить",
+    "saved": "Сохранено",
+    "appearance": "Внешний вид",
+    "theme": "Тема",
+    "theme_dark": "Тёмная",
+    "theme_light": "Светлая",
+    "theme_system": "Как в системе",
+    "password": "Пароль",
+    "current_password": "Текущий пароль",
+    "new_password": "Новый пароль",
+    "repeat_password": "Повторите пароль",
+    "change_password": "Сменить пароль",
+    "password_changed": "Пароль изменён. Другие устройства вышли из аккаунта.",
+    "sessions": "Устройства",
+    "session_current": "Это устройство",
+    "session_last_used": "Активность: {{date}}",
+    "session_end": "Завершить",
+    "logout_all": "Выйти на всех устройствах"
+  },
+  "form": {
+    "show_password": "Показать пароль",
+    "hide_password": "Скрыть пароль",
+    "passwords_mismatch": "Пароли не совпадают",
+    "required": "Заполните поле",
+    "cancel": "Отмена",
+    "close": "Закрыть",
+    "copy": "Копировать",
+    "copied": "Скопировано"
+  },
+  "loading": "Загрузка…",
+  "route_error": {
+    "reload": "Обновить страницу"
   }
 }