feat(gui): add OriginSelectorWidget for file origin selection (#13)

- 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

src/Gui/Action.cpp

@@ -54,6 +54,7 @@
 #include "Workbench.h"
 #include "WorkbenchManager.h"
 #include "WorkbenchSelector.h"
+#include "OriginSelectorWidget.h"
 #include "ShortcutManager.h"
 #include "Tools.h"
 
@@ -1470,4 +1471,25 @@ void WindowAction::addTo(QWidget* widget)
     }
 }
 
+// --------------------------------------------------------------------
+
+OriginSelectorAction::OriginSelectorAction(Command* pcCmd, QObject* parent)
+    : Action(pcCmd, parent)
+{}
+
+OriginSelectorAction::~OriginSelectorAction() = default;
+
+void OriginSelectorAction::addTo(QWidget* widget)
+{
+    if (widget->inherits("QToolBar")) {
+        auto* toolbar = static_cast<QToolBar*>(widget);
+        auto* selector = new OriginSelectorWidget(widget);
+        toolbar->addWidget(selector);
+    }
+    else {
+        // For menus, just add the action
+        widget->addAction(action());
+    }
+}
+
 #include "moc_Action.cpp"