feat(ui): add box selection feature

- Selection: add addAll() method for bulk shape addition
- Controller: box selection with mouse drag on empty space
- ShapeDraftman: drawSelectionBox() for rubber-band rendering
- ShapesView: currentSelectionBox field and setter

src/main/java/ovh/gasser/newshapes/ui/ShapeDraftman.java

@@ -135,7 +135,7 @@ public class ShapeDraftman implements ShapeVisitor {
         if ((selAttrs != null) && (selAttrs.selected)){
             Rectangle bounds = s.getBounds();
             this.g2d.setColor(Color.RED);
-            int handleSize = 5;
+            int handleSize = 10;
             this.g2d.drawRect(bounds.x - handleSize, bounds.y - handleSize, handleSize, handleSize);
             this.g2d.drawRect(bounds.x + bounds.width, bounds.y + bounds.height, handleSize, handleSize);
             if (resizeMode) {
@@ -149,4 +149,14 @@ public class ShapeDraftman implements ShapeVisitor {
         }
     }
 
+    public void drawSelectionBox(Rectangle box) {
+        if (box == null) return;
+        g2d.setXORMode(Color.WHITE);
+        g2d.setColor(Color.BLUE);
+        g2d.setStroke(new BasicStroke(1, BasicStroke.CAP_BUTT,
+                BasicStroke.JOIN_MITER, 1, new float[]{4, 4}, 0));
+        g2d.drawRect(box.x, box.y, box.width, box.height);
+        g2d.setPaintMode();
+    }
+
 }