ChatController class

Controller that manages chat state and behavior.

This controller extends ScrollController to provide scrolling functionality while also managing message state, dispatch operations, and failed message handling. It follows the Single Responsibility Principle by focusing on chat-specific state management.

Key responsibilities:

• Message state management
• Scroll behavior control
• Message dispatch and retry logic
• Failed message tracking
• Stream-based event notifications

Example usage:

final controller = ChatController();
controller.addMessage(message);
controller.dispatchMessage(
  message,
  onDispatch: (msg) async {
    // Send message to server
    return processedMessage;
  },
);