ci: add GitHub Actions workflow with ruff and E2E tests

- Add CI workflow running Ruff lint/format checks
- Run full E2E cycle (Docker Compose + Playwright + tests)
- Refactor code formatting to satisfy Ruff (line breaks, readability)
- Use sys.executable in tests for interpreter-agnostic execution

https://chatgpt.com/share/694a7f81-d96c-800f-88cb-7b25b4cdfe1a

src/matomo_bootstrap/__init__.py

@@ -4,4 +4,5 @@ Headless bootstrap tooling for Matomo:
 - readiness checks
 - admin/API token provisioning
 """
+
 __all__ = []