feat: when restored position has no nodes in viewport, automatically fit to view (#7435)

## Summary

Sometimes the saved position is super far away from any of the nodes,
which causes general confusion. This PR changes the `loadGraphData`
logic to fit-to-view in those scenarios.

Fixes https://github.com/Comfy-Org/ComfyUI_frontend/issues/7425

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-7435-feat-when-restored-position-has-no-nodes-in-viewport-automatically-fit-to-view-2c86d73d36508119bf2ed9d361ec868f)
by [Unito](https://www.unito.io)

---------

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

src/scripts/app.ts

@@ -64,6 +64,7 @@ import type { ComfyExtension, MissingNodeType } from '@/types/comfy'
 import { type ExtensionManager } from '@/types/extensionTypes'
 import type { NodeExecutionId } from '@/types/nodeIdentification'
 import { graphToPrompt } from '@/utils/executionUtil'
+import { anyItemOverlapsRect } from '@/utils/mathUtil'
 import { collectAllNodes, forEachNode } from '@/utils/graphTraversalUtil'
 import {
   getNodeByExecutionId,
@@ -1222,13 +1223,19 @@ export class ComfyApp {
         if (graphData.extra?.ds) {
           this.canvas.ds.offset = graphData.extra.ds.offset
           this.canvas.ds.scale = graphData.extra.ds.scale
+
+          // Fit view if no nodes visible in restored viewport
+          this.canvas.ds.computeVisibleArea(this.canvas.viewport)
+          if (
+            !anyItemOverlapsRect(
+              this.rootGraph._nodes,
+              this.canvas.visible_area
+            )
+          ) {
+            requestAnimationFrame(() => useLitegraphService().fitView())
+          }
         } else {
-          // @note: Set view after the graph has been rendered once. fitView uses
-          // boundingRect on nodes to calculate the view bounds, which only become
-          // available after the first render.
-          requestAnimationFrame(() => {
-            useLitegraphService().fitView()
-          })
+          requestAnimationFrame(() => useLitegraphService().fitView())
         }
       }
     } catch (error) {