feat: add documentation and version comparison tools

[christian-andersson]

Summary

Adds two new MCP tools to help AI agents understand GitHub Actions documentation and changes between versions:

• get_action_documentation - Fetch README documentation for any action at a specific version/ref
• compare_action_versions - Compare releases between two versions with full changelog and release notes

Motivation

The existing analyze_workflow tool identifies which actions need updates, but doesn't provide:

• Documentation for understanding how to use actions
• Changelogs explaining what changed between versions
• Release notes to assess breaking changes

These new tools fill that gap by providing detailed context for upgrade decisions.

Changes

New Tools

get_action_documentation

• Fetches README.md at a specific version, tag, branch, or commit
• Smart ref resolution: explicit ref > version > default branch
• Returns full markdown documentation

Example usage:

get_action_documentation(action: "actions/checkout@v4")
get_action_documentation(action: "actions/checkout", ref: "main")

compare_action_versions

• Compares all releases between two versions
• Shows full release notes for each version
• Classifies updates as major/minor/patch
• Provides summary statistics
• Flags major updates with ⚠️ warning

Example usage:

compare_action_versions(action: "actions/checkout@v4.0.0", target_version: "v6.0.0")

Infrastructure Changes

• Added GitHubRepository and GitHubContent types
• Added body field to GitHubRelease for release notes
• Added getRepository(), getDefaultBranch(), and getFileContent() methods to GitHub client

Workflow for AI Agents

1. analyze_workflow → "These 5 actions are outdated"
2. compare_action_versions → "Here's what changed" (release notes)
3. get_action_documentation → "Here's how to use the new version" (if needed)

Testing

• ✅ Type checking (deno check)
• ✅ Linting (deno lint)
• ✅ Formatting (deno fmt)
• ✅ Manual testing via MCP reconnect

🤖 Generated with Claude Code