Add UI server with real-time updates and update-ui command

[wesen]

This PR introduces a significantly enhanced UI server with real-time update
capabilities and a new update-ui command:

UI Server Improvements

• Implemented Server-Sent Events (SSE) for real-time UI updates without page
  refreshes
• Added file watching to automatically reload pages when YAML files change
• Improved routing with proper URL paths and handler registration
• Added structured logging with different log levels for actions
• Implemented proper error handling and graceful shutdown
• Enhanced component styling and rendering for lists and forms
• Added support for nested lists and improved visual hierarchy

New Update-UI Command

• Added new MCP command to dynamically update UI components
• Supports YAML input for defining components
• Converts YAML to JSON before sending to the server
• Includes comprehensive documentation in README
• Provides multiple conversion methods (Python, yq, or basic sed)

UI Action Handling

• Added /api/ui-action endpoint for component event handling
• Implemented comprehensive form data collection
• Added smart logging that prioritizes important events
• Added tracking of which button triggered form submissions
• Maintained backward compatibility with existing console logging

Example Pages

• Added dinosaur and farm-themed example pages showcasing UI capabilities
• Includes interactive forms, quizzes, and information displays
• Demonstrates nested components and list structures

Documentation

• Enhanced UI DSL documentation with better examples
• Added comprehensive documentation for UI action handling
• Added structured metadata for better document retrieval
• Created developer documentation for SSE page handling