feat: Implement chained line drawing with Esc key exit

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

src/ViewportWidget.cpp

@@ -8,6 +8,7 @@
 #include "SketchObject.h"
 #include "ApplicationController.h"
 #include <QMouseEvent>
+#include <QKeyEvent>
 #include <QWheelEvent>
 #include <QApplication>
 #include <QPainter>
@@ -181,7 +182,7 @@ void ViewportWidget::mousePressEvent(QMouseEvent *event)
             m_isDefiningLine = true;
         } else {
             emit lineAdded(m_firstLinePoint, p);
-            m_isDefiningLine = false;
+            m_firstLinePoint = p;
         }
         update();
     } else {
@@ -221,6 +222,18 @@ void ViewportWidget::wheelEvent(QWheelEvent *event)
     update();
 }
 
+void ViewportWidget::keyPressEvent(QKeyEvent *event)
+{
+    if (event->key() == Qt::Key_Escape) {
+        if (m_isDefiningLine) {
+            m_isDefiningLine = false;
+            update();
+            return;
+        }
+    }
+    QOpenGLWidget::keyPressEvent(event);
+}
+
 void ViewportWidget::onSketchModeStarted(SketchPlane plane)
 {
     m_currentPlane = plane;