v3.0.0

Breaking Changes

• Replace the monolithic sprint ledger decree/sprints/ledger.yaml with a
  directory store (state.yaml plus one live/<DOC-ID>.yaml file per
  membership and one closed/<SPRINT-ID>.yaml archive per closed sprint);
  existing projects must run decree migrate sprint-ledger --apply once.

Features

• Add decree sprint complete and decree sprint drop to record item-level
  outcomes mid-sprint; the one-file-per-membership sprint store makes parallel
  worktree development conflict-free.

Documentation

• Add Homebrew version and install badges to the README.