fix(install): checkout -f -B <branch> FETCH_HEAD to avoid a divergent local branch
reset --hard FETCH_HEAD updates the content but leaves the CURRENT local branch (e.g. main,
when switching to the stable channel) pointing at the other branch's commit — git status
then reports "diverged from origin/main". checkout -f -B <branch> FETCH_HEAD makes the local
branch BE the target branch at the fetched tip: still robust (needs no origin/<branch> ref) and
forced (deploy), with no divergent-branch state and a clean channel switch.
- scripts/install.sh — both the installer's update step and the generated klonkt-update now use
git checkout -qf -B <branch> FETCH_HEAD
Co-Authored-By: Claude <noreply@…>