Registry of all Mithril UI components with AI-friendly metadata.

Each component includes:

• name - Component identifier
• module - Elixir module path
• category - Component category (actions, forms, feedback, etc.)
• description - Brief description of the component
• use_when - Scenarios when this component is appropriate
• do_not_use_when - Scenarios when another component is better
• related - Related components that work well together
• alternatives - Alternative components for similar use cases
• variants - Available style variants
• a11y - Accessibility information