add debug draw mode for balancing target

src/balancing/ArenaView.h

@@ -39,6 +39,7 @@ public:
 protected:
     void paintGL() override;
     void mousePressEvent(QMouseEvent* event) override;
+    void keyPressEvent(QKeyEvent* event) override;
 
 private slots:
     void onFrame();
@@ -51,6 +52,8 @@ private:
     void drawStations(QPainter& painter);
     void drawScrap(QPainter& painter);
     void drawShips(QPainter& painter);
+    void drawDebugSensorRanges(QPainter& painter);
+    void drawDebugTargetLines(QPainter& painter);
     void drawBeams(QPainter& painter);
 
     float tilePx() const;
@@ -86,4 +89,6 @@ private:
     bool m_finishedEmitted;
 
     std::optional<entt::entity> m_selectedEntity;
+
+    bool m_debugDraw;
 };