revert(editor): restore the canonical arrow toggle

Merged
J1
2mo ago
+39-246

Summary

Restore the previous arrow toggle for canonical subblock input modes while the compact icon switch is completed in a separate follow-up.

Reverts #7527.

Type of Change

  • Bug fix

Testing

  • Verified the resulting tree exactly matches the parent of the original switch commit.
  • 28 subblock tests passed.
  • Biome and bun run check:api-validation passed.

Checklist

  • Code follows project style guidelines
  • Self-reviewed my changes
  • Tests added/updated and passing (existing tests passed; exact revert)
  • No new warnings introduced
  • I confirm that I have read and agree to the terms outlined in the Contributor License Agreement (CLA)

Screenshots/Videos

No new capture; this restores the prior UI.