When beads directory is redirected to a different repository (via bd-arjb),
gitCommitBeadsDir() was running git add from the current working directory's
repo root instead of the beads directory's repo root, causing exit status 128.
This fix adds the same redirect handling already present in gitHasBeadsChanges()
and gitHasUncommittedBeadsChanges() - checking GetRedirectInfo() and using
filepath.Dir(beadsDir) as the repo root when redirected.
Fixes: git add failed: exit status 128 errors during bd sync
f36c8f6556