task(C3fin2): snap marks and selection handles wired to canvas events

frontend/src/components/CanvasArea.tsx

@@ -154,6 +154,30 @@ const CanvasArea: React.FC<CanvasAreaProps> = ({
           hitTest: (wx, wy, tol) => renderEngine.hitTest(wx, wy, tol),
         }),
       });
+
+      // ── Task C3fin: Snap-Marks + Selection-Handles im Pixi-Overlay ──
+      if (pixi && USE_PIXI_RENDERER) {
+        // Snap-Marks bei Mausbewegung (wenn ein V2-Tool aktiv ist):
+        const snapMove = (e: PointerEvent) => {
+          if (!dispatcherRef.current?.getActive()) return;
+          const rect = canvas.getBoundingClientRect();
+          const world = zoomPan.screenToWorld(e.clientX - rect.left, e.clientY - rect.top);
+          const snapResult = snapEngine.snap(world.x, world.y);
+          const marks = snapResult.point
+            ? [{ x: snapResult.point.x, y: snapResult.point.y, type: (snapResult.point as { type?: string }).type ?? 'snap' }]
+            : [];
+          pixi!.setSnapPoints(marks);
+        };
+        canvas.addEventListener('pointermove', snapMove);
+
+        // Selection-Handles bei Änderung:
+        const origSetIds = selectionEngine.selectByIds.bind(selectionEngine);
+        selectionEngine.selectByIds = (ids: string[], additive: boolean) => {
+          origSetIds(ids, additive);
+          const selected = v2Doc.getAllElements().filter((el) => ids.includes(el.id));
+          pixi!.setSelection({ selectedIds: ids, elements: selected });
+        };
+      }
       logger.info('InteractionDispatcher v2 aktiviert (VITE_TOOL_DISPATCHER=v2)');
     }