[dfederm]

Summary

Adds visible progress feedback while JellyBox validates a server connection or performs
username/password sign-in. The existing LoadingOverlay is bound to
ConnectCommand.IsRunning on Server Selection and SignInCommand.IsRunning on Login, reusing the
current busy-state sources without changing interaction behavior.

Quick Connect intentionally remains unchanged because its dialog displays an actionable
authorization code while waiting for user input.

Why this is safe

• Limited to two XAML views and the existing LoadingOverlay control.
• Reuses command IsRunning state; no authentication or connection logic changes.
• Existing IsInteractable enablement bindings remain unchanged.
• The generated Login binding maps SignInCommand.IsRunning directly from Boolean to
  Visibility.

Validation

Test / build	Result
Debug x64 solution build	Passed with 0 warnings and 0 errors
Automated tests	No automated test project exists in the repository