Document Homebrew release installation

[jordancalhoun]

Summary

• make Homebrew the README quick-start path for the swiftpkg formula and swiftpkgr cask
• document upgrade, uninstall, signed installer, app archive, CLI archive, and checksum resources for 0.3.1
• add a responsive Homebrew installation and release-resources section to the marketing site
• update the site's remaining release references and calls to action from 0.3.0 to 0.3.1

Why

The signed 0.3.1 release is published and the official Homebrew tap now exposes both the CLI formula and desktop-app cask. The public documentation should make those installation paths discoverable while retaining direct downloads for managed deployments.

User impact

Users can copy the appropriate Homebrew command directly from the README or marketing site, see the platform requirement for each tool, and reach every immutable 0.3.1 release resource without searching through the release page.

Validation

• confirmed the formula and cask definitions in codecarton/homebrew-tap
• confirmed all five linked resources against the published v0.3.1 release
• validated HTML tag structure, internal anchors, and local resource references
• validated CSS brace structure
• confirmed no stale 0.3.0 references remain in the README or site
• ran git diff --check

Closes #3

Summary by CodeRabbit

• Documentation

  • Added a Quick Start guide with Homebrew installation commands.
  • Added signed release download instructions for swiftpkg 0.3.1, including updated verification steps.
  • Clarified package-based uninstall instructions.

• Website

  • Updated installation, release, and desktop app content to highlight version 0.3.1.
  • Added direct links to CLI and desktop downloads and release resources.
  • Improved responsive layouts and styling for installation information across screen sizes.

[coderabbitai]

Caution

Review failed

The pull request is closed.

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro Plus

Run ID: 5cb898de-f181-4ea8-9982-227e31ed8954

📥 Commits

Reviewing files that changed from the base of the PR and between 972e5f0 and 3e0eef1.

📒 Files selected for processing (3)

• README.md
• site/index.html
• site/styles.css

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📝 Walkthrough

Walkthrough

The README and website now document swiftpkg 0.3.1 installation through Homebrew and signed release artifacts. Website metadata, release links, desktop app messaging, and responsive installation styles were also updated.

Changes

Distribution refresh

Layer / File(s)	Summary
Installation documentation README.md	Installation instructions add Homebrew commands, concrete 0.3.1 signed artifacts, updated verification commands, and package-based uninstall wording.
Website installation content site/index.html	Metadata, navigation, hero content, installation links, desktop app messaging, and release calls to action now reference the 0.3.1 distribution.
Installation layout styles site/styles.css	Adds installation card and release-resource styling, responsive single-column behavior, and smaller code text on narrow screens.

Estimated code review effort: 2 (Simple) | ~15 minutes

Possibly related PRs

• codecarton/swiftpkg#6: Updates related 0.3.x marketing content and website installation styling.
• codecarton/swiftpkg#16: Overlaps with the 0.3.1 signed release artifact and installer documentation updates.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch feature/homebrew-release

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