Allow paste images into freeform question input

Describe the feature or problem you'd like to solve

When the CLI agent asks a question via its interactive "Question" prompt UI, and you use the freeform text answer (either a no-choices question, or selecting "Other (type your answer)" on a multiple-choice question), the resulting input box does not accept pasting of screenshots

Proposed solution

If Copilot is going to use the freeform answer to ask me a question, i need the ability to paste a screen shot just like i would if i was answering Copilot normally

Example prompts or workflows

No response

Additional context

No response

まず、CLI agent のインタラクティブな Question prompt UI と、その自由形式テキスト入力の処理を追跡します。Copilot に通常回答するときに使われる既存の入力経路と比較し、選択肢のない質問と “Other (type your answer)” フローの両方での動作を確認します。両方の自由形式ケースでスクリーンショットを貼り付けられれば完了です。