Add a login/register toggle to ConnectPage backed by a new
useRegisterMutation (register -> /auth/me, mirroring login). The toggle
is shown only when REGISTRATION_ENABLED, resolved with the same
precedence as the API base URL: runtime window.__APP_CONFIG__ >
PUBLIC_ENABLE_REGISTRATION env > default true. The prod runtime-config
script injects the runtime flag. The backend's ALLOW_REGISTRATION stays
the real authority; this only gates the UI. EN/RU strings added.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Senko-san
538cfb9c5b