Per-channel rollback playbook and tooling

Create runbooks for per-channel rollback procedures:
- CDN / GitHub Releases: mark bad release as pre-release
- npm: `npm deprecate` + move `latest` tag back
- Homebrew: revert formula
- winget: submit manifest revert
- APT: re-point repo metadata
- Workloads (NuGet): unlist (never delete)

From the [CLI release design](https://github.com/Azure/azure-functions-core-tools/pull/5391), follow-up item #12.

Start with the CLI release design PR #5391 and follow-up item #12. Document rollback runbooks for CDN/GitHub Releases, npm, Homebrew, winget, APT, and NuGet, including the specified rollback action for each channel. Done means every listed channel has a clear procedure and the related tooling needs are recorded.

Written by the indexing model from the issue text.