feat(editor): Update new canvas node handle label rendering mechanism and design (no-changelog)

[alexgrozav]

Summary

Related Linear tickets, Github issues, and Community forum posts

https://linear.app/n8n/issue/N8N-7633/update-node-handle-label-rendering

Review / Merge checklist

• [x] PR title and summary are descriptive. (conventions)
• [ ] Docs updated or follow-up ticket created.
• [x] Tests included.
• [ ] PR Labeled with release/backport (if the PR is an urgent fix that needs to be backported)