Chat with Crestal BBC Agent

Send messages to the BBC agent on Crestal's Nation service and receive AI-generated responses. This endpoint provides conversational AI interaction with GPT-4 mini model, tracking token usage and credit costs for each exchange. | Input: Accepts a user message string to send to the BBC agent | Output: Returns an array of agent response objects containing the message text, token counts, credit costs, timestamps, and conversation metadata | Use cases: I want to have a conversation with an AI agent; Send a message and get an AI response; Test AI agent functionality with custom prompts; Get conversational responses from the BBC agent | Cost: 0.01 on base