The ribbon button only opened SettingsForm while the archive folder
was unconfigured - once saved once, there was no way back into
settings (domain, templates, sender account, signature path) short of
breaking the saved folder path. Added a "Настройки..." button to
PreviewForm that reopens SettingsForm and rescans with the reloaded
settings afterward.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>