Introduce a cron-triggered auto-release workflow that runs on the second Sunday of each month,
creating a time-based tag in YYYY-MM format and dispatching the release workflow.
The release workflow is extended with a workflow_dispatch trigger accepting a tag input, so it can be
invoked both by tag pushes and programmatically by the auto-release. Version extraction is unified
via a dedicated step using `inputs.tag || github.ref_name` in both jobs.
Co-authored-by: Copilot <copilot@github.com>
