chore(release): build cross-platform binaries and update Homebrew tap

[wax911]

Background

stackctl should be distributed as compiled binaries so users and GitHub Actions consumers do not need Deno installed. Homebrew distribution will be handled through AniTrend/homebrew-tap.

Goals

• Add release workflow for cross-platform binaries.
• Package release artifacts using a stable naming convention.
• Generate checksums.
• Publish GitHub Releases.
• Trigger or document update flow for AniTrend/homebrew-tap.

Required release targets

• x86_64-apple-darwin
• aarch64-apple-darwin
• x86_64-unknown-linux-gnu
• aarch64-unknown-linux-gnu

Required asset naming

stackctl-v<version>-x86_64-apple-darwin.tar.gz
stackctl-v<version>-aarch64-apple-darwin.tar.gz
stackctl-v<version>-x86_64-unknown-linux-gnu.tar.gz
stackctl-v<version>-aarch64-unknown-linux-gnu.tar.gz
checksums.txt

Each tarball should contain:

stackctl
README.md
LICENSE

Workflow requirements

Create .github/workflows/release.yml triggered by tags:

on:
  push:
    tags:
      - "v*"

Steps:

• Checkout.
• Setup Deno.
• Run format, lint, check, tests.
• Compile all targets.
• Package tarballs.
• Generate SHA256 checksums.
• Publish GitHub release.

Homebrew integration

This repository should not store the Homebrew formula. The formula belongs in AniTrend/homebrew-tap.

This repository should either:

1. Document the manual formula update process, or
2. Trigger/open a PR against AniTrend/homebrew-tap after a release.

Preferred final state: automated PR to AniTrend/homebrew-tap with updated formula URLs and SHA256 values.

Acceptance criteria

• Tagging v0.1.0 produces all four platform tarballs.
• checksums.txt contains SHA256 for every tarball.
• Release artifacts use the agreed naming convention.
• AniTrend/stackctl/setup can install from the release assets.
• Documentation explains how Homebrew tap updates are handled.

Non-goals

• Do not maintain Homebrew formula files in this repository.
• Do not require Homebrew for direct binary installation.
• Do not publish npm packages.