[Improve] Refine mobile task chrome

[roomote-roomote]

Created by Roomote. Follow up by mentioning @roomote-roomote, in the web UI, or in Slack.

What changed

• Render request-input questions in task messages as muted, left-bordered paragraphs instead of italic inline text.
• Refine the sandbox task view's mobile header with a card background, no outline, and tighter right padding while retaining desktop padding.

Why this change was made

The task conversation UI now presents quoted agent questions as clearly separated context, and the mobile task chrome better matches the app's card surface without an unnecessary border treatment.

Impact

Mobile task views have a cleaner header without affecting desktop spacing. Request-input replies more clearly distinguish the agent's question from the user's response. Focused UI tests and the pre-push checks passed; the available seeded tasks did not include a request-input response state for complete visual capture.

[roomote-roomote]

No code issues found. See task

_{Reviewed 50fc8e9}