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/security-audit.yml

@@ -15,7 +15,7 @@ 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