Function enable_auto_merge 

pub fn enable_auto_merge(pr_number: usize) -> Result<()>

Enable GitHub auto-merge for a pull request (squash strategy).

Invokes: gh pr merge <PR_NUMBER> --auto --squash --delete-branch. Schedules a squash merge to occur automatically once required status checks and reviews pass. If all requirements are already satisfied, merge occurs immediately.

Errors

• Spawning or executing gh pr merge fails.
• Command exits non-zero (propagated by [ytil_cmd::CmdExt]).