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>

docker-compose.yml

@@ -15,6 +15,10 @@ x-base: &base
 services:
   builder:
     <<: *base
+    # Put builder on the same network as server/client/equipment_py so
+    # one-off `docker compose run --rm builder /app/build/secs_interop_probe ...`
+    # commands can DNS-resolve peer services by their compose name.
+    networks: [secs]
     command:
       - bash
       - -lc
@@ -51,6 +55,26 @@ services:
     command: ["/app/build/secs_client", "--host", "server", "--port", "5000", "--device", "0"]
     networks: [secs]
 
+  # Python container preloaded with secsgem-py 0.3.0 for cross-validation
+  # of our C++ HSMS/SECS-II/GEM implementation against the reference library.
+  interop:
+    build: ./interop
+    volumes:
+      - .:/app
+    working_dir: /app/interop
+    networks: [secs]
+
+  # secsgem-py running as passive equipment so the C++ active host can
+  # connect to it.  Used by tools/run_interop.sh which then launches
+  # `secs_interop_probe --host equipment_py`.
+  equipment_py:
+    build: ./interop
+    volumes:
+      - .:/app
+    working_dir: /app/interop
+    command: ["python3", "/app/interop/passive_equipment.py", "--port", "5000"]
+    networks: [secs]
+
 networks:
   secs: {}