hooks: scope the Husky chain marker to the hooks directory that set it

ENTIRE_CHAINED_HOOK held only the hook name. A git operation the user's Husky hook runs in another Entire repo inherits it, and a plain Entire hook there never clears it, so that repo's entire hooks git pre-push was skipped along with its checkpoint push and privacy filter.

The marker is now "<hook>:<hooks dir>", resolved in the shell with pwd -P (pwd -W first, for Git for Windows) and CDPATH cleared so cd cannot print into it. entire hooks git skips only when the hook matches and the directory is the same file as its own repo's hooks directory; any resolution failure runs Entire.

The old name-only marker is not accepted: this chain has not shipped.