CI/CD hardening: lint, secret scan, coverage gate, auto CVE-fix PRs, GHCR + GitHub mirror publishing (#34)

- release changelog: commits rendered as description (link), divider lines dropped
- gitleaks secret scan and hadolint on every push/PR
- ruff lint/format gate (Python repos) with a pytest --cov-fail-under gate
- scheduled CRITICAL Trivy failures attempt an apk upgrade rebuild and open a follow-up PR if it clears the finding, instead of just failing red
- images also published to ghcr.io/djeex/<repo>
- a matching GitHub Release is created on the GitHub mirror, with a notice pointing back to this repo as the source of truth

Dockerfile

@@ -27,6 +27,13 @@ RUN pip install --no-cache-dir -r requirements-dev.txt
 COPY ./tests/ ./tests/
 COPY ./demo/ ./demo/
 
+FROM base AS lint
+
+RUN pip install --no-cache-dir ruff==0.16.4
+COPY ruff.toml /app/ruff.toml
+COPY ./tests/ ./tests/
+RUN ruff check . && ruff format --check .
+
 FROM base
 
 ENTRYPOINT ["/app/entrypoint.sh"]