Mirrors SpoolStore: per-record file with atomic .tmp+rename, magic+
version-prefixed binary layout, replay on enable, delete on remove.
FSMs gain a restore_state() that bypasses the transition table and
handlers since a replay isn't a transition.
Six new tests cover write+restart+replay across every CIDS/CSMS/CAS
axis, remove-deletes-journal, malformed-record drop-not-poison, and
the persistence-disabled no-op path.
Closes#1 in the test-gap backlog.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
