paperclip#10978 made destructive replacement an explicit caller choice
in their skill-sync and package-import paths: a rerun must never remove
operator edits by default. Our hub-skill updater had the same hazard --
'hermes skills update' calls do_install(force=True), which rmtree-replaces
the skill directory even when the user edited it after install.
do_update now compares the on-disk content hash against the hash the
lockfile recorded at install time; drifted skills are skipped with a
notice and only overwritten with the new --force flag (CLI + /skills
slash path). Bundled skills already had this protection via the
user-modified manifest in hermes update; this brings hub-installed
skills to parity.
Sabotage-verified: disabling the drift check makes the new skip test fail.
0e378e59aa