Shared utilities and components used by both frontend and backend.

• JsonRpcViewer.js - Main application class that orchestrates all functionality
• MessageParser.js - Handles parsing of JSON Lines and Content-Length formatted input
• MessageGrouper.js - Groups messages into request-response pairs and handles filtering
• MessageRenderer.js - Creates DOM elements and handles visual representation
• utils.js - Shared utility functions and constants

The shared components follow a modular design:

1. Parser - Extracts JSON-RPC messages from raw input
2. Grouper - Organizes messages and applies filters
3. Renderer - Creates visual elements
4. Viewer - Orchestrates all components and handles user interactions

This separation allows for easy testing, maintenance, and potential reuse in other contexts.