persistence: ProcessJobStore + ControlJobStore enable_persistence(dir)

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>

CMakeLists.txt

@@ -108,6 +108,7 @@ add_executable(secsgem_tests
   tests/test_loader.cpp
   tests/test_process_jobs.cpp
   tests/test_control_jobs.cpp
+  tests/test_job_persistence.cpp
   tests/test_exceptions.cpp
   tests/test_carrier_state.cpp
   tests/test_carriers.cpp