Automate releases from PR titles and clean up CI workflows.

Add release and PR title checks, shared CI scripts, Gitea PR template, and align pyproject.toml to v0.3.1.

Co-authored-by: Cursor <[email protected]>

.gitea/workflows/publish.yml

@@ -17,17 +17,13 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@v5
         with:
-          python-version: ${{ inputs.python-version }}
+          python-version-file: .python-version
 
       - name: Install uv
         run: pip install uv
 
       - name: Update version in pyproject.toml to match tag
-        run: |
-          TAG_VERSION="${GITHUB_REF##*/}"
-          VERSION="${TAG_VERSION#v}"
-          sed -i.bak -E "s/^version = \".*\"/version = \"${VERSION}\"/" pyproject.toml
-          rm pyproject.toml.bak
+        run: scripts/ci/bump-version.sh --from-tag "${GITHUB_REF##*/}"
 
       - name: Build package
         run: |