- Create OriginSelectorWidget class (QToolButton with dropdown menu)
- Add OriginSelectorAction to create widget in toolbars
- Add Std_Origin command registered in CommandStd.cpp
- Add widget to File toolbar (before New/Open/Save)
- Connect to OriginManager fastsignals for origin changes
- Add Catppuccin Mocha styling for the widget
- Widget shows current origin name/icon with connection status overlay
This implements Issue #13: Origin selector toolbar widget
