fix(install): reset to FETCH_HEAD so updates work across branch/refspec (fixes "origin/stable unknown revision")
git fetch origin <branch> only updates FETCH_HEAD, not refs/remotes/origin/<branch>, on a
single-branch/shallow clone (or one originally on a different branch) — so `reset --hard
origin/stable` failed with "fatal: ambiguous argument 'origin/stable'", notably when switching
an existing main install to the stable channel. Reset to FETCH_HEAD instead, which always points
at what was just fetched.
- scripts/install.sh — both the installer's re-run update step and the generated klonkt-update
now
reset --hard FETCH_HEAD instead of origin/$KLONKT_BRANCH
Co-Authored-By: Claude <noreply@…>