Per-job binary record (.pj / .cj) with magic+version, atomic
.tmp+rename. PJ store additionally writes an order.idx index file
that preserves HOQ-aware queue position across restarts.
Rcpvars / prprocessparams (secs2::Item variants) are intentionally
out of scope for v1 — they're optional E40 trailers and need a body
codec round-trip; callers re-populate via set_e40_extras() after
restart.
Five new tests cover full lifecycle replay (Processing mid-run +
HOQ-reordered queue), dequeue-deletes-file, corrupt-record drop,
CJ state + PJ-list replay, and CJ remove cleanup.
Closes#3 in the test-gap backlog.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
