docs: add AI skills for X packages

[victorcg88]

Summary

Adds comprehensive AI skills documentation for Interface X monorepo and key packages to enable AI-assisted development.

What's Changed

Skills Created

Root Skill (skills/x-skilld/SKILL.md)

• Overview of Interface X monorepo structure
• Development commands and workflows
• Package conventions and architecture
• Commit and release practices

Package Skills

• x-components: Vue 3 component library usage guide
• x-adapter: API client creation documentation
• x-tailwindcss: Design system plugin guide

Configuration Updates

• Added skills directory to published files in package.json for:
  • @empathyco/x-components
  • @empathyco/x-adapter
  • @empathyco/x-tailwindcss
• Added skills to ESLint ignore patterns to prevent linting markdown files

Dependencies

• Added skilld package to enable AI skill system

Benefits

✅ AI agents can understand monorepo structure and conventions
✅ Package consumers get context-aware assistance
✅ Skills are published with packages automatically
✅ Two-tier documentation: monorepo contributors + package users

Testing

Skills follow the required format with:

• YAML frontmatter with name and description
• Comprehensive documentation sections
• Code examples and usage patterns
• Best practices and troubleshooting

Skills are compatible with skilld-aware AI assistants like GitHub Copilot.