install.sh clones from the mirror first (falls back to github.com if
unreachable); mbs update fetches origin (mirror) first, falls back to
a github remote if that fetch fails. Mirror itself is a bare repo on
финка2, kept in sync from GitHub every 10 min via an authenticated
token (needed because that box's IP gets rate-limited/blocked by
GitHub for anonymous git clones).
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>