docs: bring the documentation up to the daemon/client era

A large gap had opened between the docs and the code: the README and
INTEGRATION guide did not mention the gRPC daemon or the Python client at
all (the entire vendor surface), ARCHITECTURE still described secs_server
as the ~1200-line canonical wiring example (it is a ~110-line thin main
over EquipmentRuntime), and test counts across six files were stale
(445/2753 -> 473/3087 core + the separate 125-assertion daemon suite).

- README: new "Integrating your tool (pick a tier)" section — Python
  client / any-language gRPC / embedded C++ — plus daemon tests and
  tools/run_interop.sh in the Testing section.
- ARCHITECTURE: layer diagram gains the vendor-surface and
  EquipmentRuntime/default_handlers tiers; stale wiring row fixed.
- INTEGRATION: three-tier chooser up front (this guide = the C++ tier).
- ch30 tour: secs_gemd + secs_gemd_tests in the binaries table.
- ch31: example alarm used a nonexistent `alcd:` field with bit 7 set
  (which the validator forbids) -> real `category:`/`name:` fields, and
  the roles: block documented.
- ch35: handler-location note now points at default_handlers.cpp's 15
  per-capability register_* functions.
- ch40: built-artifacts list + sample output counts.
- ch50: secsgem::gem runtime/default_handlers/handler_slot/name_index
  includes + new secsgem::daemon namespace section.
- PROOFS: test-count table gains the runtime/handlers/daemon row so the
  tally adds up; daemon suite noted. VERIFICATION/COMPLIANCE counts.
- interop/README: the one-command runner + the two daemon-track harnesses
  (daemon_interop, pyclient_interop).

Audited via a docs-vs-code sweep (the audit itself under-reported: it
validated counts textually; reality was 473/3087).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

docs/35_state_machines_and_dispatch.md

@@ -59,7 +59,9 @@ router->on(2, 41, [model](const auto& m) {
   return messages::s2f42(ack);
 });
 
-// ...one per S/F pair.  apps/secs_server.cpp registers ~50.
+// ...one per S/F pair.  The default GEM set (56) lives in
+// src/gem/default_handlers.cpp, decomposed into 15 per-capability
+// register_* functions; register_default_handlers(runtime) wires them all.
 ```
 
 The `examples/pvd_tool/main.cpp` §6 register 51 handlers in ~460