feat(ci): add automatic Homebrew tap publishing

[platinummonkey]

Summary

Configures automatic Homebrew formula publishing to DataDog/homebrew-pack when releases are tagged. Users will be able to install pup via brew install datadog/pack/pup for easier distribution and automatic updates.

Changes

• .goreleaser.yml: Added brews configuration for homebrew-pack tap with formula metadata, install instructions, and test commands
• .github/workflows/release.yml: Added HOMEBREW_TAP_TOKEN environment variable to GoReleaser step
• README.md: Updated installation section to feature Homebrew as primary method
• CLAUDE.md: Updated Quick Start with Homebrew installation instructions
• docs/HOMEBREW_TAP_SETUP.md: New comprehensive setup guide with prerequisites, PAT creation, testing procedures, and troubleshooting

Manual Steps Required

Before this can work in production, the following manual setup is needed:

1. Create Fine-grained Personal Access Token

• Navigate to https://github.com/settings/tokens?type=beta
• Create token with:
  • Name: pup-homebrew-tap-publisher
  • Repository access: Only DataDog/homebrew-pack
  • Permissions: Contents: Read and Write

2. Add GitHub Secret

• Go to https://github.com/DataDog/pup/settings/secrets/actions
• Add new secret:
  • Name: HOMEBREW_TAP_TOKEN
  • Value: The PAT created above

3. Verify homebrew-pack Repository

• Ensure https://github.com/DataDog/homebrew-pack exists
• Ensure it's public (or the PAT has access)
• The Formula/ directory will be created automatically if missing

Testing Plan

The setup guide includes instructions for testing with a pre-release:

# Create test release
git tag -a v0.9.0-beta.1 -m "Test Homebrew tap"
git push origin v0.9.0-beta.1

# Verify formula was published
# Check: https://github.com/DataDog/homebrew-pack/blob/main/Formula/pup.rb

# Test installation
brew tap datadog/pack
brew install pup
pup version

Documentation

See docs/HOMEBREW_TAP_SETUP.md for:

• Complete step-by-step setup instructions
• Testing procedures
• Troubleshooting common errors
• Security best practices
• Token maintenance guidelines

References

• GoReleaser Homebrew Documentation
• Homebrew Tap Guide
• GitHub Fine-grained PAT Guide

---

🤖 Generated with Claude Code

[github-actions]

📊 Test Coverage Report

Overall Coverage: 80.4%

Threshold: 80% ✅

Coverage by Package

## Coverage by Package

- github.com/DataDog/pup/pkg/auth/callback/server.go:40: 81.2%
- github.com/DataDog/pup/pkg/auth/dcr/client.go:28: 100.0%
- github.com/DataDog/pup/pkg/auth/dcr/types.go:24: 100.0%
- github.com/DataDog/pup/pkg/auth/oauth/client.go:22: 100.0%
- github.com/DataDog/pup/pkg/auth/oauth/pkce.go:24: 85.7%
- github.com/DataDog/pup/pkg/auth/storage/factory.go:53: 94.7%
- github.com/DataDog/pup/pkg/auth/storage/keychain.go:44: 42.9%
- github.com/DataDog/pup/pkg/auth/storage/storage.go:58: 71.4%
- github.com/DataDog/pup/pkg/auth/types/types.go:23: 100.0%
- github.com/DataDog/pup/pkg/client/client.go:32: 94.4%
- github.com/DataDog/pup/pkg/config/config.go:22: 100.0%
- github.com/DataDog/pup/pkg/formatter/formatter.go:31: 100.0%
- github.com/DataDog/pup/pkg/useragent/useragent.go:32: 100.0%
- github.com/DataDog/pup/pkg/util/time.go:20: 95.8%

## Summary

total:								(statements)		80.4%

---

📈 Coverage Status: ✅ PASSED - Coverage meets minimum threshold

_{Updated for commit c5a1ff0}

[platinummonkey]

depends on datadog-labs/homebrew-pack#3