feat(installer): bring channel-aware installer/updater onto rc (cherry-pick #54)

[chr1syy]

Bring the channel-aware installer onto rc

Cherry-picks #54 (the opt-in RC release channel) from main onto rc, so the rc branch — and therefore RC release tarballs cut from it — carry the channel-aware install.sh + maestro-relay-ctl, not just the release.yml prerelease marking that rc already had.

Why

main and rc had diverged: main got #54's channel installer, but rc only got the release.yml prerelease change (added when cutting v0.5.0-rc.1). That left a rough edge — the RC tarball's bundled maestro-relay-ctl lacked the channel / update --rc commands, and $CONFIG_DIR/channel written at install wasn't read back. This closes that gap so an RC install can stay on the rc channel across update.

What's included (from #54, final squashed form)

• install.sh: MAESTRO_RELAY_CHANNEL (stable|rc), channel-aware resolve_release, validates the channel up front, persists it to $CONFIG_DIR/channel on install.
• maestro-relay-ctl: update --rc/--stable, channel subcommand, explicit MAESTRO_RELAY_VERSION pins preserved, unknown channels normalized to stable.
• README: channel docs.

The one conflict (the deploy usage line) was resolved to keep rc's multi-provider wording and the new update/channel lines. release.yml already had the identical prerelease line (deduped to one).

Verification

• bash -n clean on both scripts; channel set/read smoke-tested
• npm run build clean; 316/316 tests pass
• No conflict markers; release.yml has exactly one prerelease: line

🤖 Generated with Claude Code

[coderabbitai]

Important

Review skipped

Auto reviews are disabled on base/target branches other than the default branch.

Please check the settings in the CodeRabbit UI or the .coderabbit.yaml file in this repository. To trigger a single review, invoke the @coderabbitai review command.

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: 3d7597a5-754a-435c-89f6-cdebaba8571a

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

Use the checkbox below for a quick retry:

• 🔍 Trigger review

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch chore/rc-channel-installer

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}