tests: E87 slot-map mismatch + multi-LP wire scenarios

Four new test cases:

  * S3F19 verify with matching map → SlotMapVerifyAck::Accept and
    CSMS lands in Read on the equipment side.
  * S3F19 verify with disagreeing map → Mismatch ack and CSMS lands
    in Mismatched.
  * 4 LPs + 4 carriers, host verifies CAR-1 (mismatch) and CAR-3
    (match) — only those two carriers move on the CSMS axis;
    CAR-2/CAR-4 stay NotRead.  Confirms per-carrier independence.
  * Multi-LP E84 handshake sequencing (load then unload) round-trips
    through Idle.  Documents that the current E84StateMachine is
    per-equipment, not per-port — a future per-port FSM would
    update this test alongside.

Closes #11 in the test-gap backlog.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

CMakeLists.txt

@@ -129,6 +129,7 @@ add_executable(secsgem_tests
   tests/test_gem300_scenario.cpp
   tests/test_wire_ceid_emission.cpp
   tests/test_live_gem300.cpp
+  tests/test_e87_wire_scenarios.cpp
 )
 target_link_libraries(secsgem_tests PRIVATE secsgem doctest::doctest)
 target_compile_definitions(secsgem_tests PRIVATE