fix: haskelseed-native Gitea Actions without GitHub marketplace

Replace actions/checkout and setup-python with internal git clone and
system python3. Drops CI matrix to a single job on the self-hosted runner.

.gitea/workflows/publish-python-package.yml

@@ -11,27 +11,24 @@ jobs:
     runs-on: haskelseed
     steps:
       - name: Check out source
-        uses: actions/checkout@v4
+        env:
+          PACKAGE_TOKEN: ${{ secrets.PACKAGE_TOKEN }}
+        run: |
+          git clone --depth 1 \
+            "https://tegwick:${PACKAGE_TOKEN}@gitea.coulomb.social/coulomb/kaizen-agentic.git" \
+            repo
+          cd repo
+          git checkout "${{ gitea.sha }}"
 
-      - name: Set up Python
-        uses: actions/setup-python@v5
-        with:
-          python-version: "3.12"
-
-      - name: Install packaging tools
-        run: python -m pip install --upgrade build twine
-
-      - name: Build distributions
-        run: python -m build
-
-      - name: Validate distributions
-        run: python -m twine check dist/*
-
-      - name: Upload to Gitea PyPI
+      - name: Build and publish
         env:
           TWINE_USERNAME: ${{ secrets.PACKAGE_USER }}
           TWINE_PASSWORD: ${{ secrets.PACKAGE_TOKEN }}
-        run: >-
-          python -m twine upload
-          --repository-url https://gitea.coulomb.social/api/packages/coulomb/pypi
-          dist/*
+        run: |
+          cd repo
+          python3 -m pip install --upgrade pip build twine
+          python3 -m build
+          python3 -m twine check dist/*
+          python3 -m twine upload \
+            --repository-url https://gitea.coulomb.social/api/packages/coulomb/pypi \
+            dist/*