Manage Change-Ledger Skill

The single home for the unified, append-only change-ledger in plan-marshall and the first-class worktree_sha freshness API over it. The skill is script-deterministic — pure record-keeping and a git-native currency hash, no LLM judgement. It is modeled on manage-locks: a tracked-config-dir primitive that is NOT plan-scoped, so it serves plan-less orchestrator builds as well as plan-scoped task builds.

There is exactly ONE ledger file, ONE worktree_sha primitive (a single shared implementation), and ONE append verb. Entries are pure-append — no find-and-update, no in-place mutation. There is no separate registry file anywhere.

The worktree_sha primitive — working-tree currency, not HEAD currency