The update-check payload now carries a `dirty: bool` reflecting the
working-tree state vs HEAD, computed via the same `git diff-index
--quiet HEAD --` primitive already used by `_dirty_suffix()`. A dirty
install at-or-past the latest release tag used to silently report
"Up to date" with no remediation affordance; the Settings panel
can now read this flag to offer `apply_force_update` (which already
does `git checkout .` + `git reset --hard` to reset to a clean
latest).
The probe is conservatively clean on real errors (timeout, missing
git, fatal) so a transient probe failure never produces a false-
positive "local changes" alert.
Closes#4085
b3nw
9bb1dc8573