AskUserQuestion card is not scrollable on mobile, making Submit unreachable

Problem

When using Kimi Web on a phone, the AskUserQuestion card (QuestionCard.vue) is not scrollable. If the question has many or long options, the card grows beyond the viewport and the Submit button becomes unreachable.

This makes it impossible to answer the agent questions from a mobile browser, which blocks any serious development workflow on a phone.

Environment

• Mobile browser (iOS Safari / Android Chrome)
• Viewport width <= 640 px

Steps to reproduce

1. Open Kimi Web on a phone.
2. Trigger an action that asks a question with several long options (e.g. a plan review or ask-user tool call).
3. Try to scroll down inside the question card to reach the Submit button.

Expected behavior

The question card body should scroll independently while the header/footer (including Submit) stay visible, so the user can select options and submit.

Actual behavior

The card extends past the bottom of the screen and cannot be scrolled, so the Submit button is off-screen and inaccessible.

Related PR

• #1388 fixes this by constraining the card height on mobile and making .ui-card__body scrollable.

Start with QuestionCard.vue and reproduce the issue at a viewport width of 640px or less using several long options. Compare the current behavior with related PR #1388, then verify that the card body can scroll and the header and Submit footer remain reachable on mobile.