[backport cloud/1.35] Fix: the wrong selection under the hand mode (#7716)

## Summary

Backport of #7541 to cloud/1.35.

Fixed an inconsistency where nodes were resizable in Hand mode. Resizing
is now restricted to Selection mode only to match standard LiteGraph
behavior (Hand mode should only be for panning).

## Changes

- Added guard clause to prevent resize in Hand mode
(`shouldHandleNodePointerEvents` check)
- Added `event.button !== 0` check for non-primary mouse buttons

## Original PR

https://github.com/Comfy-Org/ComfyUI_frontend/pull/7541

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-7716-backport-cloud-1-35-Fix-the-wrong-selection-under-the-hand-mode-2d16d73d365081c7b558f652952bb590)
by [Unito](https://www.unito.io)

---------

Co-authored-by: GitHub Action <action@github.com>

src/renderer/extensions/vueNodes/components/LGraphNode.vue

@@ -327,6 +327,8 @@ const { startResize } = useNodeResize((result, element) => {
 })
 
 const handleResizePointerDown = (event: PointerEvent) => {
+  if (event.button !== 0) return
+  if (!shouldHandleNodePointerEvents.value) return
   if (nodeData.flags?.pinned) return
   startResize(event)
 }