Function resolve_effective_cwd 

pub fn resolve_effective_cwd(
    ito_path: &Path,
    change_id: Option<&str>,
    worktree: &WorktreeConfig,
) -> ResolvedCwd

Resolve the effective working directory for a Ralph invocation.

When worktrees are enabled and a matching worktree exists for change_id, returns the worktree path. Otherwise falls back to the process’s current working directory.