Add T hotkey for temporary blueprint from selection

src/lib/eventsystem/event/TemporaryBlueprintRequestedEvent.h

@@ -0,0 +1,9 @@
+#pragma once
+
+#include "Event.h"
+
+// Emitted when the player presses the temporary-blueprint hotkey (REQ-UI-BLUEPRINT-TEMP).
+// Carries no payload: the blueprint is built from the current selection by the receiver.
+class TemporaryBlueprintRequestedEvent : public Event
+{
+};