fix: RAF-batch canvas ResizeObserver to stop link overlay redraw lag

The canvas-element ResizeObserver runs resizeCanvas() (which does
canvas.width = NaN, getBoundingClientRect, and a full draw(true, true))
on every fire. During an animated bottom-panel splitter open or window
drag, the RO fires many times per second, producing visible link overlay
redraw lag because the link overlay canvas re-syncs its size via useRafFn
the frame after each main canvas resize.

Wrap the callback in createRafBatch() so at most one resize+draw runs
per animation frame. Multiple RO fires within the same frame coalesce
into a single draw using the latest container dimensions.

src/scripts/app.ts

@@ -8,6 +8,7 @@ import { useCanvasPositionConversion } from '@/composables/element/useCanvasPosi
 import { layoutStore } from '@/renderer/core/layout/store/layoutStore'
 import { syncLayoutStoreNodeBoundsFromGraph } from '@/renderer/core/layout/sync/syncLayoutStoreFromGraph'
 import { flushScheduledSlotLayoutSync } from '@/renderer/extensions/vueNodes/composables/useSlotElementTracking'
+import { createRafBatch } from '@/utils/rafBatch'
 
 import { st, t } from '@/i18n'
 import { ChangeTracker } from '@/scripts/changeTracker'
@@ -949,10 +950,16 @@ export class ComfyApp {
 
     this.rootGraph.start()
 
-    // Ensure the canvas fills the window
+    // Coalesce ResizeObserver bursts during splitter / window drags into one
+    // resize per frame to stop redundant draw(true, true) calls and the link
+    // overlay redraw lag they cause.
+    const scheduleCanvasResize = createRafBatch(() => {
+      const canvasEl = this.canvasElRef.value
+      if (canvasEl) this.resizeCanvas(canvasEl)
+    })
     useResizeObserver(this.canvasElRef, ([canvasEl]) => {
       if (canvasEl.target instanceof HTMLCanvasElement) {
-        this.resizeCanvas(canvasEl.target)
+        scheduleCanvasResize.schedule()
       }
     })