chore(claude): add new-release skill

[l-hellmann]

Type

chore - tooling, housekeeping

Description

Adds a project-level Claude Code skill at .claude/skills/new-release/ that walks the existing zcli release flow end-to-end:

1. Pre-flight - on main, clean tree, in sync with origin/main, main.yml green at HEAD.
2. Decide version - reads the recent tags and commits since the last stable, proposes the next version (next rc, next patch rc0, or promote-rc-to-stable), waits for confirmation.
3. Open a release PR (stable only) - drafts a CHANGELOG.md entry classified by conventional-commit prefix, branches release/vX.Y.Z, commits, pushes, and opens a PR. Pre-releases skip this entirely.
4. Resume after the PR merges - re-entered when the user says "the release PR is merged" / "continue the release"; verifies the PR merged, syncs main, re-checks CI, surfaces drift commits.
5. Create the release - drafts custom GitHub release notes (categorized, PR-linked, with a compare/... Full Changelog link) instead of --generate-notes; writes them to a temp file; runs gh release create --target main --notes-file ... (plus --prerelease for rcs).
6. Watch the pipeline - follows the release.yml run (goreleaser, publish-npm, smoke-test) and reports per-job outcomes.
7. Verify - confirms uploaded assets, npm dist-tag (latest vs next), and returns the release URL.

Key safety property: every mutating action (git push, gh pr create, gh release create, gh release delete, gh run rerun) shows the exact command and waits for explicit user confirmation before running. Read-only gh calls (run list, run view, release view) flow freely so monitoring stays snappy.

The skill is wired to trigger on phrases like "cut a release", "new release", "ship a new version", "promote to stable", and also re-triggers on "the release PR is merged" / "continue the release" to enter phase 2.

Test plan

• Pre-release flow: invoke on a small -rc0 bump, confirm it skips step 3 (no PR) and lands at step 5 directly.
• Stable flow: cut the next stable, confirm the release/vX.Y.Z PR opens with a sensible CHANGELOG draft, then after merge the skill resumes correctly and creates the release with custom notes (not --generate-notes).
• Pause behavior: confirm the skill stops and quotes the exact command before each mutating gh / git push call.

Breaking changes

None.