Support pasting nodes when switching workflow tabs; currently, you need one more click to activate the canvas

Support pasting nodes even when users haven't clicked on the canvas.

## Feature details

Currently, users need to click on the canvas once when pasting nodes to a new workflow.

https://github.com/user-attachments/assets/07658e58-25e1-42c6-9217-62af554c5e2d

If users don't click on the canvas, users can't paste the nodes. This feature request is to make it work too.

https://github.com/user-attachments/assets/7d7af6c8-ccc7-4fc8-811b-aa682d691c85

## Problem want to solved:
Found some users have trouble using the paste feature. Some of them don't know they need one more click to activate the canvas to paste the node.
Related issues:
- https://github.com/comfyanonymous/ComfyUI/issues/8481
- https://github.com/Comfy-Org/ComfyUI_frontend/issues/5683

┆Issue is synchronized with this [Notion page](https://www.notion.so/Issue-5844-Support-pasting-nodes-when-switching-workflow-tabs-currently-you-need-one-more-click-27d6d73d3650818d9b14f76797da39a5) by [Unito](https://www.unito.io)