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.

.gitea/workflows/publish.yml

@@ -0,0 +1,37 @@
+name: Publish to PyPI Registry
+
+on:
+  release:
+    types: [created, published]
+  workflow_dispatch:
+
+jobs:
+  publish:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v3
+
+      - name: Setup Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: '3.11'
+
+      - name: Install build tooling
+        run: python -m pip install --upgrade pip build twine
+
+      - name: Run tests
+        run: |
+          python -m pip install -e '.[dev]'
+          python -m pytest -q
+
+      - name: Build package
+        run: python -m build
+
+      - name: Publish to Gitea PyPI registry
+        env:
+          TWINE_USERNAME: sa-dc-build
+          TWINE_PASSWORD: ${{ secrets.SA_DC_BUILD_API_TOKEN }}
+          TWINE_REPOSITORY_URL: https://git.dragonchain.com/api/packages/dragonchain/pypi
+        run: twine upload --non-interactive dist/*