Inline 'settings' slash commands should be invokable at any point in prompt, and return to prompt

Feature Description

Typing /model in the middle of a prompt leaves it as a raw string, i should be able to invoke /model, go to model, change it, then return to my prompt as if nothing happened and i never typed /model.

Use Case

Often i find myself mid way through a prompt unable to switch my model, or do some settings lookup without removing my entire prompt, doing the lookup then repasting. Would be nice if it allowed that invocation mid way through a prompt, even if its just restricted to the hardcoded settings commands.

Additional Context

I want this ^^^

here:

How important is this to you?

Important for my workflow

未指定任何檔案或測試。先找出 prompt 輸入處理，以及現有硬編碼的設定命令 dispatch，接著追蹤命令執行如何變更 prompt 狀態。完成的標準是：可以在 prompt 的中間呼叫 /model 和其他受支援的設定命令，同時原始 prompt 保持完整，並在之後還原。