Agent Skills: release

Cuts the release itself — derives the next semantic version from commits since the last tag, writes plain-English patch notes, previews the plan, then on confirmation creates an annotated tag plus GitHub release, or dispatches the repo's guarded release workflow where production sits behind a workflow_dispatch promote gate. Trunk-based; no develop or staging branch promotion. Assumes the trunk is already green — to open a release PR or wait on required checks first, use `release-pr-gates`.