conformance: standalone secs_conformance harness binary

The closest thing to an in-repo "RTS" — a runnable executable that
points at any HSMS-SS equipment and walks through every E30
fundamental + additional capability, reporting pass/fail per check
and exiting with the right code for CI / canary use.

  build/secs_conformance --host <ip> --port 5000 --device 0

Each check sends a host-initiated primary and asserts the equipment
replies with the expected stream/function within T3.  Checks chain
forward through async callbacks (each reply handler kicks off the
next check) so the conformance run stays inside one io.run().

Initial check set (mirrors COMPLIANCE.md §3 fundamentals):
  E37 §7.2  SELECT handshake
  E30 §6.5  S1F13/F14 Establish Comms
  E30 §6.7  S1F1/F2 Are You There
  E30 §6.13 S1F11/F12 SVID Namelist
  E30 §6.16 S2F29/F30 ECID Namelist
  E30 §6.20 S2F17/F18 Clock
  E30 §6.14 S5F5/F6 List Alarms
  E30 §6.17 S7F19/F20 PP List
  E30 §6.10 S1F19/F20 GEM Compliance

Validated against the demo server: 9/9 PASS.

README.md §8 (Compliance + certification) updated to point at the
harness as the suggested first-line conformance check.  Tool
vendors fork apps/secs_conformance.cpp and add their own
capability-specific checks alongside.

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

CMakeLists.txt

@@ -83,6 +83,9 @@ target_link_libraries(secs_client PRIVATE secsgem)
 add_executable(secs_interop_probe apps/secs_interop_probe.cpp)
 target_link_libraries(secs_interop_probe PRIVATE secsgem)
 
+add_executable(secs_conformance apps/secs_conformance.cpp)
+target_link_libraries(secs_conformance PRIVATE secsgem)
+
 # --- Tests ----------------------------------------------------------------
 enable_testing()
 include(FetchContent)