Follow-up to #3530733: Impossible to set a URL or SRC of an SDC with AI

Follow-up to #3530733: Introduce AI Agents and tools to Build Pages from components

Overview

This prompt won't set the url on the requested button
Place a button with link to https://new.drupal.org/ai

We can see the LLM answer is correct,

But for some reason XB doesn't take it in consideration and keep using default value set by the examples key.
Same issue for image.src prop.

I modified the instructions like this to be sure llm generates the links:

        *   **Links:** If a URL is not specified in the prompt, always use `href: "#"` 
        *   **Images:** Configure `aspect_ratio` and other non-content props, If a SRC is not specified in the prompt,  **NEVER** generate `src` or `alt` props.

Proposed resolution

User interface changes