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/python/pyproject.toml

@@ -0,0 +1,31 @@
+[build-system]
+requires = ["setuptools>=68"]
+build-backend = "setuptools.build_meta"
+[project]
+name = "mcias-client"
+version = "0.1.0"
+description = "Python client library for the MCIAS identity and access management API"
+requires-python = ">=3.11"
+license = { text = "MIT" }
+dependencies = [
+    "httpx>=0.27",
+]
+[project.optional-dependencies]
+dev = [
+    "pytest>=8",
+    "respx>=0.21",
+    "mypy>=1.10",
+    "ruff>=0.4",
+]
+[tool.setuptools.packages.find]
+where = ["."]
+include = ["mcias_client*"]
+[tool.mypy]
+strict = true
+python_version = "3.11"
+[tool.ruff]
+target-version = "py311"
+line-length = 88
+
+[tool.ruff.lint]
+select = ["E", "F", "W", "I", "UP"]