move blueprints out of the sidebar into Ctrl+C / Ctrl+V dialogs

src/lib/eventsystem/event/BlueprintSaveRequestedEvent.h

@@ -0,0 +1,11 @@
+#pragma once
+
+#include "Event.h"
+
+// Ctrl+C: save the current building selection as a named blueprint
+// (REQ-UI-BLUEPRINT-CREATE, REQ-UI-HOTKEYS). MainWindow owns the modal flow, because
+// it is the only widget that can pause the game and raise the dim overlay; whether
+// anything placeable is selected is decided there, not by the key handler.
+class BlueprintSaveRequestedEvent : public Event
+{
+};