* Ask for the model and harness used in AI-assisted PRs
Add an AGENTS.md rule that agents name the model and harness in the PR
description, and a matching line under the LLM checkbox in the pull
request template so human contributors fill it in too.
* Only let agents fill the LLM line of the PR template
Agents leave the description template to the developer and only fill in
the LLM line with the model and harness used.
* Set up GitHub generated release notes.
* Remove Towncrier from the release script.
* Add changelog failures for Labels with Danger and stop requesting a changelog file.
* Update changelog documentation.