Redesign LLM answer UI +add collapsible context and model metadata.

Revamps the LLM answer HTML template with a modern, collapsible UI, feedback buttons, and an info modal displaying model and context details. Updates the plugin to wrap answers with data attributes for model name and context, and moves all layout logic to the template. Also adds a new codemod script for generating prompt XML from selected files in VS Code.

Author: bearlike