Pause option for Q chat

## Problem
Users have no option to pause a response when they decide to & have to wait until Q Finishes responding

## Expected behavior
When user hits pause, Q Should stop responding, this way it saves tokens as well as space for the user in the chat window.

The issue names no files, tests, or entry points. Start by locating the Q chat response flow and its existing controls, then trace how an in-progress response can be stopped; done means a user can pause a response and the chat stops receiving further output while preserving the conversation state.

Written by the indexing model from the issue text.