Implement Phase 9: client libraries (Go, Rust, Lisp, Python)

- clients/README.md: canonical API surface and error type reference
- clients/testdata/: shared JSON response fixtures
- clients/go/: mciasgoclient package; net/http + TLS 1.2+; sync.RWMutex
  token state; DisallowUnknownFields on all decoders; 25 tests pass
- clients/rust/: async mcias-client crate; reqwest+rustls (no OpenSSL);
  thiserror MciasError enum; Arc<RwLock> token state; 22+1 tests pass;
  cargo clippy -D warnings clean
- clients/lisp/: ASDF mcias-client; dexador HTTP, yason JSON; mcias-error
  condition hierarchy; Hunchentoot mock-dispatcher; 37 fiveam checks pass
  on SBCL 2.6.1; yason boolean normalisation in validate-token
- clients/python/: mcias_client package (Python 3.11+); httpx sync;
  py.typed; dataclasses; 32 pytest tests; mypy --strict + ruff clean
- test/mock/mockserver.go: in-memory mock server for Go client tests
- ARCHITECTURE.md §19: updated per-language notes to match implementation
- PROGRESS.md: Phase 9 marked complete
- .gitignore: exclude clients/rust/target/, python .venv, .pytest_cache,
  .fasl files
Security: token never logged or exposed in error messages in any library;
TLS enforced in all four languages; token stored under lock/mutex/RwLock

clients/rust/target/debug/.fingerprint/icu_provider-a4e85089dd94f53b/invoked.timestamp

@@ -0,0 +1 @@
+This file has an mtime of when this was started.

clients/rust/target/debug/.fingerprint/icu_provider-a4e85089dd94f53b/lib-icu_provider

@@ -0,0 +1 @@
+ccd4fcb9c35ac725

clients/rust/target/debug/.fingerprint/icu_provider-a4e85089dd94f53b/lib-icu_provider.json

@@ -0,0 +1 @@
+{"rustc":16243257175721966122,"features":"[\"baked\"]","declared_features":"[\"alloc\", \"baked\", \"deserialize_bincode_1\", \"deserialize_json\", \"deserialize_postcard_1\", \"export\", \"logging\", \"serde\", \"std\", \"sync\", \"zerotrie\"]","target":8134314816311233441,"profile":5347358027863023418,"path":6149871022819322100,"deps":[[697207654067905947,"yoke",false,14518097974934810925],[3966877249195716185,"icu_locale_core",false,8738334886186839694],[5298260564258778412,"displaydoc",false,6580091290351767530],[6160379875186348458,"zerotrie",false,779555625856432278],[13225456964504773423,"writeable",false,15579303433905778912],[14563910249377136032,"zerovec",false,3103798927038060636],[17046516144589451410,"zerofrom",false,3054016906148176177]],"local":[{"CheckDepInfo":{"dep_info":"debug/.fingerprint/icu_provider-a4e85089dd94f53b/dep-lib-icu_provider","checksum":false}}],"rustflags":[],"config":2069994364910194474,"compile_kind":0}