v1.3.0: Git hooks for quality enforcement

Features

Git Hooks for the Agent

The action now automatically installs lightweight, standalone git hooks in target repositories before running the pi agent:

• commit-msg: Enforces Conventional Commits format
• prepare-commit-msg: Auto-appends issue numbers from branch names

These hooks:

• ✅ Have no dependencies - pure shell scripts
• ✅ Work with any language/stack (Python, Go, Rust, etc.)
• ✅ Respect existing hooks - only install if no hook exists
• ✅ Don't modify package.json or install npm packages

Development Quality (for pi-action contributors)

• Add Husky + commitlint for enforcing commit conventions
• Pre-commit hook: tests, typecheck, lint, build verification, dist/ freshness check
• Pre-push hook: coverage thresholds (80% lines/functions, 70% branches)

Refactoring

From issue #10:

• Extract shared types (GitHubReaction, GitHubUser, AgentResult)
• Add test helpers (createMockGitHubClient, createTriggerInfo)
• Extract utility functions (getErrorMessage, formatSuccessComment, formatErrorComment)
• Use discriminated union for AgentResult (makes invalid states unrepresentable)
• Handle empty agent responses
• Clear timeout timer on success

Usage

- uses: cv/pi-action@v1.3.0
  with:
    github_token: ${{ secrets.GITHUB_TOKEN }}
    pi_auth_json: ${{ secrets.PI_AUTH_JSON }}