* fix(worktree-watcher): surface external push -u through the git-common watch
An external-shell 'git push -u' writes only the common .git/config (plus
refs/remotes/<remote>/<branch>), both invisible to the git-common event
filter, so the Checks panel stayed on 'No upstream configured' until the
renderer safety poll. Classify the common config and remote-tracking refs
as status-tier signals, poll config alongside the other primary-checkout
metadata files, and keep FETCH_HEAD/reflog/ref-lock churn ignored.
* fix(worktree-watcher): refresh after subsequent pushes
