interop: secsgem-py cross-validation harness + lenient identifier parsing

Adds a Docker-based interop harness that drives the C++ server with
secsgem-py 0.3.0 as the active host and probes a secsgem-py-passive
equipment from a minimal C++ active client.  Surfaces and fixes four
interoperability bugs uncovered by cross-testing:

  * SEMI E5 identifier formatcodes are a U1|U2|U4|U8 wildcard;
    secsgem-py picks the narrowest fitting width while our parsers
    only accepted U4.  `as_uN_scalar` / `as_iN_scalar` now accept
    any unsigned/signed width and range-check the downcast.
  * PPBODY (S7F3/F6) is "ASCII | Binary | List" per the spec;
    secsgem-py defaults to ASCII.  Added BINARY_OR_ASCII codegen
    item type with `as_text_or_binary` accessor.
  * S1F23/F24 Collection Event Namelist was unimplemented; added
    schema + `vids_for(ceid)` accessor on EventReportSubscriptions
    plus the dispatch handler.
  * S10F1 was registered as a host->equipment handler, but per
    SEMI E5 §12 S10F1 is equipment->host; S10F3 is the actual
    host->equipment Terminal Display Single.  Added an S10F3
    handler alongside (we keep S10F1 too for backward compat).

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

interop/passive_equipment.py

@@ -0,0 +1,94 @@
+"""Run secsgem-py as passive equipment so a C++ active host can drive it.
+
+Listens on 0.0.0.0:<port>, waits to be reached by an active host.
+secsgem-py's GemEquipmentHandler answers S1F13/F14 (establish
+communications), S1F17/F18 (online request), S1F1/F2 (are-you-there)
+out of the box.  Status variables, equipment constants, and one
+collection event are registered so that S1F3/S1F11/S1F23 round-trip
+yield non-empty bodies.
+"""
+
+from __future__ import annotations
+
+import argparse
+import logging
+import signal
+import sys
+import threading
+
+import secsgem.common
+import secsgem.gem
+import secsgem.hsms
+import secsgem.secs.variables as v
+
+
+LOG = logging.getLogger("interop.equipment")
+
+
+class InteropEquipment(secsgem.gem.GemEquipmentHandler):
+    def __init__(self, settings):
+        super().__init__(settings)
+
+        # One status variable so S1F3/F11 yield a non-empty list.
+        sv = secsgem.gem.StatusVariable(1, "ChamberTemp", "C", v.U4)
+        sv.value = 25
+        self.status_variables[1] = sv
+
+        # One equipment constant.
+        self.equipment_constants[10] = secsgem.gem.EquipmentConstant(
+            10, "EnergyCap", 0, 100, 50, "kW", v.U4
+        )
+
+        # One collection event (visible via S1F23).
+        self.collection_events[1001] = secsgem.gem.CollectionEvent(
+            1001, "DemoEvent", []
+        )
+
+
+def main() -> int:
+    ap = argparse.ArgumentParser()
+    ap.add_argument("--port", type=int, default=5000)
+    ap.add_argument("--session-id", type=int, default=0)
+    ap.add_argument("--log-level", default="INFO")
+    args = ap.parse_args()
+    logging.basicConfig(
+        level=args.log_level,
+        format="%(asctime)s %(levelname)s %(name)s: %(message)s",
+    )
+    if args.log_level.upper() != "DEBUG":
+        logging.getLogger("communication").setLevel(logging.WARNING)
+        logging.getLogger("hsms_connection").setLevel(logging.WARNING)
+
+    settings = secsgem.hsms.HsmsSettings(
+        address="0.0.0.0",
+        port=args.port,
+        session_id=args.session_id,
+        connect_mode=secsgem.hsms.HsmsConnectMode.PASSIVE,
+        device_type=secsgem.common.DeviceType.EQUIPMENT,
+    )
+
+    eq = InteropEquipment(settings)
+    eq.enable()
+
+    LOG.info("passive equipment listening on 0.0.0.0:%d session=%d",
+             args.port, args.session_id)
+
+    stop = threading.Event()
+    def shutdown(_signo, _frame):
+        LOG.info("signal received, stopping")
+        stop.set()
+    signal.signal(signal.SIGINT, shutdown)
+    signal.signal(signal.SIGTERM, shutdown)
+
+    try:
+        stop.wait()
+    finally:
+        try:
+            eq.disable()
+        except Exception as e:  # noqa: BLE001
+            LOG.warning("disable raised: %s", e)
+    return 0
+
+
+if __name__ == "__main__":
+    sys.exit(main())