feat: add zoom scale options

Memola/Canvas/View/Bridge/ViewController/CanvasViewController.swift

@@ -162,6 +162,12 @@ extension CanvasViewController {
             }
             .store(in: &cancellables)
 
+        canvas.zoomPublisher
+            .sink { [weak self] zoomScale in
+                self?.zoomChanged(zoomScale)
+            }
+            .store(in: &cancellables)
+
         tool.$selectedPen
             .sink { [weak self] pen in
                 self?.penChanged(to: pen)
@@ -298,6 +304,12 @@ extension CanvasViewController {
     }
 }
 
+extension CanvasViewController {
+    func zoomChanged(_ zoomScale: CGFloat) {
+        scrollView.setZoomScale(zoomScale, animated: true)
+    }
+}
+
 extension CanvasViewController {
     func historyUndid() {
         guard history.undo() else { return }