feat: Manage active drawing tool state in controller and UI

Co-authored-by: aider (gemini/gemini-2.5-pro) <aider@aider.chat>

src/ApplicationController.cpp

@@ -34,6 +34,21 @@ SketchFeature* ApplicationController::activeSketch() const
     return m_activeSketch;
 }
 
+ApplicationController::ToolType ApplicationController::activeTool() const
+{
+    return m_activeTool;
+}
+
+void ApplicationController::setActiveTool(ToolType tool)
+{
+    if (m_activeTool == tool) {
+        return;
+    }
+
+    m_activeTool = tool;
+    emit activeToolChanged(m_activeTool);
+}
+
 void ApplicationController::newDocument()
 {
     m_activeSketch = nullptr;
@@ -114,6 +129,7 @@ void ApplicationController::beginSketchCreation()
 void ApplicationController::endSketch()
 {
     m_activeSketch = nullptr;
+    setActiveTool(ToolType::None);
     emit sketchModeEnded();
 }