Function is_branch_changing_command 

pub fn is_branch_changing_command(command: &str) -> bool

Check if a shell command might change the git branch.

Returns true for commands like:

• git checkout <branch>
• git switch <branch>
• git worktree add <path>
• git merge <branch> (in case of fast-forward)
• git rebase <branch>

This is a heuristic and may have false positives/negatives.