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/40_building_running_demo.md

@@ -53,7 +53,9 @@ build/
 ├── secs_conformance     47-check conformance harness
 ├── secs_interop_probe   active host probing secsgem-py equipment
 ├── secs_bench           throughput/latency bench
-├── secsgem_tests        the 445-case doctest binary
+├── secsgem_tests        the 473-case doctest binary
+├── secs_gemd            gRPC daemon: HSMS equipment + name-based tool API
+├── secs_gemd_tests      in-process gRPC service tests (when grpc++ present)
 └── pvd_tool             worked PVD-tool example
 ```
 
@@ -74,8 +76,8 @@ Runs `secsgem_tests` end-to-end.  Expected output:
 [doctest] doctest version is "2.4.11"
 [doctest] run with "--help" for options
 ===============================================================================
-[doctest] test cases:  445 |  445 passed | 0 failed | 0 skipped
-[doctest] assertions: 2753 | 2753 passed | 0 failed |
+[doctest] test cases:  473 |  473 passed | 0 failed | 0 skipped
+[doctest] assertions: 3087 | 3087 passed | 0 failed |
 [doctest] Status: SUCCESS!
 ```