TTS logic for Listen Better demo

tts.ts

    ...

    const systemPrompt = getDialogueSystemPrompt();
    const humanMessageContent = `Here's the dialogue script inside triple backticks:\n\n\`\`\`\n${script}\n\`\`\`\n\nNow generate the AUDIO, NOT TEXT, for this dialogue script.`;
    const messages = [
      new HumanMessage(`${systemPrompt}\n\n${humanMessageContent}`),
    ];

    const result = await model.invoke(messages);

    ...