[Feedback]: Add ability to edit previous prompts in chat history

What problem are you trying to solve?

Cursor and other AI IDEs let you click/edit a previous prompt in the conversation history and re-run from there. Command Code's chat doesn't support this — to re-run a past prompt you can only copy it manually.

What would improve it?

It would be a big UX improvement to let users edit any prior message inline, then submit the whole thread from that point (regenerating the assistant response from the edited message).

What do you do today?

Just keep sending the edits in next prompts.

Product area

Chat and composer

该 issue 只指出了 Chat 和 composer 产品区域；没有提供文件、测试或入口点。首先定位聊天历史和 composer 组件，然后跟踪提交 prompt 如何创建 Assistant 响应。当可以编辑并重新提交之前的用户消息，并从该点重新生成 thread 时，即视为完成。