Need feature to upload image in VS code extension

## Problem
Currently Amazon Q does not have option to attach images. Due to this If I have to ask it to create new UI using image it does not support it whereas cursor or other AI extensions does support this feature.

## Expected behavior
There should be option to attach image in chat and then we can ask agent to refer the attached image, mimic and generate the UI components. This will be time saving as currently it does require multiple chat iterations to get the work done.

Start by locating the VS Code extension's chat UI and message-input flow, then trace how chat requests are sent to Amazon Q. Define how an attached image reaches the agent and how the UI exposes it. Done means a user can attach an image in chat and ask Amazon Q to use it when generating UI components.

Written by the indexing model from the issue text.