feat(plugins): create pr-title-validator hook plugin

[JacobPEvans]

Create Claude Code hook plugin for PR title validation.

Repository: jacobPEvans/claude-code-plugins

Implements

• PreToolUse hook on Bash (gh pr create)
• Validates PR title format
• AI-friendly error messages
• Type suggestions

Tasks

• Create plugin structure
• Implement validation logic
• Add comprehensive tests
• Document hook usage

Related

• Depends on: ci(.github): add branch naming validation (GitHub Action) #32 (PR title validation)
• Reference: https://github.com/jacobPEvans/claude-code-plugins

Epic

Implements #30