persistence: CarrierStore + LoadPortStore enable_persistence(dir)

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>

include/secsgem/gem/load_port_state.hpp

@@ -104,6 +104,14 @@ class LoadPortStateMachine {
   bool on_reservation_event(LoadPortReservationEvent e);
   bool on_association_event(LoadPortAssociationEvent e);
 
+  // Direct state-restore (persistence replay only).  See carrier_state.hpp.
+  void restore_state(LoadPortTransferState tx, LoadPortReservationStatus rs,
+                     LoadPortAssociationStatus as) {
+    tx_state_ = tx;
+    rs_state_ = rs;
+    as_state_ = as;
+  }
+
  private:
   LoadPortTransferTable    tx_table_;
   LoadPortReservationTable rs_table_;