Language comes from the gnexus-auth account profile by default; Settings
now hosts a per-service override that survives logouts and profile-webhook
syncs (users table keeps profile JSON verbatim, override in a separate
column that the upsert never touches). Open mode stores the choice in
localStorage.

- backend: users table (zero-migration, IF NOT EXISTS), app/locales.py
  (normalize_locale/effective_locale), users upsert on session create and
  user.updated webhook, GET /me returns locale + locale_effective,
  new PATCH /api/v1/me (cookie-session only; 'auto'/'""' clears override)
- frontend: hand-rolled i18n mirror of gnexus-creds (locale ref, t() with
  Slavic plurals, EN fallback), full dictionaries (~130 strings), <html
  lang> + <title> tracked via watch; SettingsPage with language picker
  (Auto/en/uk/ru); ServerCard/ServerPage/StoragePage status triple and
  table columns unified into reactive computed t() lookups; fmtAgo/
  fmtUptime localized; nav/login/shell translated; default html lang en

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