Implement T hotkey for temporary blueprint from selection

Add a TemporaryBlueprintRequestedEvent emitted by GameWorldView on the T
key. BlueprintPanel handles it by building a blueprint from the current
selection (reusing createBlueprintFromSelection) and entering placement
mode via BlueprintPlacementRequestedEvent, without adding it to the list
or persisting it. Right-click exits and discards the temporary blueprint
through the existing exit path. No-op when nothing placeable is selected.

Implements REQ-UI-BLUEPRINT-TEMP.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VGNNLeFWhVzvxkK9qVXP2K

src/lib/eventsystem/event/CMakeLists.txt

@@ -22,6 +22,7 @@ SET(HDRS
 	${CMAKE_CURRENT_SOURCE_DIR}/DemolishModeToggleRequestedEvent.h
 	${CMAKE_CURRENT_SOURCE_DIR}/BlueprintPlacementRequestedEvent.h
 	${CMAKE_CURRENT_SOURCE_DIR}/ExitBlueprintModeRequestedEvent.h
+	${CMAKE_CURRENT_SOURCE_DIR}/TemporaryBlueprintRequestedEvent.h
 	${CMAKE_CURRENT_SOURCE_DIR}/SpeedChangeRequestedEvent.h
 	${CMAKE_CURRENT_SOURCE_DIR}/LayoutDialogRequestedEvent.h
 	${CMAKE_CURRENT_SOURCE_DIR}/RecipeSelectionRequestedEvent.h

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
+{
+};

src/ui/BlueprintPanel.cpp

@@ -339,3 +339,17 @@ void BlueprintPanel::handleEvent(std::shared_ptr<const BlueprintModeExitedEvent>
 {
     clearActiveBlueprintButton();
 }
+
+void BlueprintPanel::handleEvent(std::shared_ptr<const TemporaryBlueprintRequestedEvent> /*event*/)
+{
+    // Temporary blueprint (REQ-UI-BLUEPRINT-TEMP): build from the current selection and
+    // enter placement mode without adding it to the list or persisting it. If nothing
+    // player-placeable is selected, do nothing.
+    Blueprint bp = createBlueprintFromSelection();
+    if (bp.buildings.empty()) { return; }
+
+    // No saved blueprint is active while a temporary one is being placed.
+    clearActiveBlueprintButton();
+    EventManager::getInstance()->sendEventImmediately(
+        std::make_shared<BlueprintPlacementRequestedEvent>(std::move(bp)));
+}

src/ui/BlueprintPanel.h

@@ -11,6 +11,7 @@
 #include "EventHandler.h"
 #include "GameConfig.h"
 #include "SelectionChangedEvent.h"
+#include "TemporaryBlueprintRequestedEvent.h"
 #include "Tick.h"
 
 class Simulation;
@@ -21,7 +22,8 @@ class QVBoxLayout;
 class BlueprintPanel : public QWidget,
                        public CombinedEventHandler<BuildingBlocksChangedEvent,
                                                    SelectionChangedEvent,
-                                                   BlueprintModeExitedEvent>
+                                                   BlueprintModeExitedEvent,
+                                                   TemporaryBlueprintRequestedEvent>
 {
     Q_OBJECT
 
@@ -33,6 +35,7 @@ private:
     void handleEvent(std::shared_ptr<const BuildingBlocksChangedEvent> event) override;
     void handleEvent(std::shared_ptr<const SelectionChangedEvent> event) override;
     void handleEvent(std::shared_ptr<const BlueprintModeExitedEvent> event) override;
+    void handleEvent(std::shared_ptr<const TemporaryBlueprintRequestedEvent> event) override;
 
 private slots:
     void onCreateClicked();

src/ui/GameWorldView.cpp

@@ -56,6 +56,7 @@
 #include "EscapeMenuRequestedEvent.h"
 #include "TracePrintRequestedEvent.h"
 #include "BuildHotkeyPressedEvent.h"
+#include "TemporaryBlueprintRequestedEvent.h"
 #include "BossWaveUpdatedEvent.h"
 #include "BuilderModeExitedEvent.h"
 #include "BlueprintModeExitedEvent.h"
@@ -1582,6 +1583,13 @@ void GameWorldView::keyPressEvent(QKeyEvent* event)
         else if (m_blueprintMode.has_value()) { exitBlueprintMode(); }
         else                                  { toggleDemolishMode(); }
         break;
+    case Qt::Key_T:
+        // Request a temporary blueprint from the current selection (REQ-UI-BLUEPRINT-TEMP).
+        // The BlueprintPanel owns the selection and blueprint-capture logic; it decides
+        // whether anything placeable is selected and drives placement mode from there.
+        EventManager::getInstance()->sendEventImmediately(
+            std::make_shared<TemporaryBlueprintRequestedEvent>());
+        break;
     case Qt::Key_Escape:
         EventManager::getInstance()->sendEventImmediately(
             std::make_shared<EscapeMenuRequestedEvent>());