Fix buttons displayed behind images in litegraph (#7627)

#7394 caused a regression with preview image buttons showing behind the
image in litegraph. This is fixed by also deferring button draws

| Before | After |
| ------ | ----- |
| <img width="360" alt="before"
src="https://github.com/user-attachments/assets/4c3b02e0-4951-403d-98b8-b01a01512d21"/>
| <img width="360" alt="after"
src="https://github.com/user-attachments/assets/7a4fb8e4-8caa-47f3-939d-8d8ddc0e71b4"
/>|

---------

Co-authored-by: github-actions <github-actions@github.com>

src/renderer/extensions/vueNodes/widgets/composables/useImagePreviewWidget.ts

@@ -265,14 +265,19 @@ const renderPreview = (
       }
     }
 
-    ctx.fillStyle = fill
-    ctx.beginPath()
-    ctx.roundRect(x, y, sz, sz, [4])
-    ctx.fill()
-    ctx.fillStyle = textFill
-    ctx.font = '12px Inter, sans-serif'
-    ctx.textAlign = 'center'
-    ctx.fillText(text, x + 15, y + 20)
+    deferredImageRenders.push(() => {
+      ctx.save()
+      ctx.setTransform(transform)
+      ctx.fillStyle = fill
+      ctx.beginPath()
+      ctx.roundRect(x, y, sz, sz, [4])
+      ctx.fill()
+      ctx.fillStyle = textFill
+      ctx.font = '12px Inter, sans-serif'
+      ctx.textAlign = 'center'
+      ctx.fillText(text, x + 15, y + 20)
+      ctx.restore()
+    })
 
     return isClicking
   }