Add proof-measure client + Gitea PyPI publish; bump to 0.4.0

proof-measure is a separate, public, unauthenticated Dragonchain service. Adds:
- UnauthenticatedClient: HMAC-free transport mirroring Client (session
  injection, allow_redirects=False, from_dict decoding).
- ProofMeasureClient: get_security / report / health; default base URL
  https://proof-measure.dragonchain.com. Standalone (ProofMeasureClient()) and
  via DragonchainSDK.proof_measure.
- Proof-measure dataclass models (decimals as strings, timestamps as int).
- .gitea/workflows/publish.yml: build + twine upload to the Gitea PyPI registry
  on release (the SDK had no publish workflow before).

Also fixes 3 pre-existing failing tests: _FakeSession.request didn't accept the
allow_redirects kwarg the client now passes (added by the prior redirect change),
so the suite was red at HEAD.

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "hatchling.build"
 
 [project]
 name = "prime-sdk-python"
-version = "0.2.0"
+version = "0.4.0"
 description = "A self-contained Python SDK for interacting with Dragonchain nodes."
 readme = "README.md"
 requires-python = ">=3.9"