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/utils/mathUtil.ts

@@ -1,6 +1,9 @@
 import type { ReadOnlyRect } from '@/lib/litegraph/src/interfaces'
 import type { Bounds } from '@/renderer/core/layout/types'
 
+/** Simple 2D point or size as [x, y] or [width, height] */
+type Vec2 = readonly [number, number]
+
 /**
  * Finds the greatest common divisor (GCD) for two numbers using iterative
  * Euclidean algorithm. Uses iteration instead of recursion to avoid stack
@@ -91,3 +94,28 @@ export function computeUnionBounds(
     height: maxY - minY
   }
 }
+
+/**
+ * Checks if any item with pos/size overlaps a rectangle (AABB test).
+ * @param items Items with pos [x, y] and size [width, height]
+ * @param rect Rectangle as [x, y, width, height]
+ * @returns `true` if any item overlaps the rect
+ */
+export function anyItemOverlapsRect(
+  items: Iterable<{ pos: Vec2; size: Vec2 }>,
+  rect: ReadOnlyRect
+): boolean {
+  const rectRight = rect[0] + rect[2]
+  const rectBottom = rect[1] + rect[3]
+
+  for (const item of items) {
+    const overlaps =
+      item.pos[0] < rectRight &&
+      item.pos[0] + item.size[0] > rect[0] &&
+      item.pos[1] < rectBottom &&
+      item.pos[1] + item.size[1] > rect[1]
+
+    if (overlaps) return true
+  }
+  return false
+}