Task page: show when a delivered answer

Found while verifying task 7568 against dev task 5138. After all three question rounds were answered, the task went back to Running and showed nothing more. The answer had in fact been swallowed: the ACP request was never decided, and the console gave no sign of it. Suggestions: 1. For an ACP run, show on the task page whether each answered round was handed to the agent and whether the agent's request was decided. An answered round whose request stays open should read as "not delivered", not as Running. 2. Flag a task that is Running but has had no agent event for N minutes since an answer was delivered, beside the Agent activity feed. 3. When one AskUserQuestion produces several rounds that share a header and a question prefix, group them visually as one question rather than as separate numbered rounds. 4. Answering several rounds one at a time gives no hint that delivery waits until the last one is answered. Say "delivered when all rounds are answered" under each round. Out of scope: the round split and answer loss themselves (fixed by task 7568); Gemini credentials; MicroVM launcher. Done means: - An ACP task whose answer was not consumed within a minute shows that state on its task page. - The rounds UI states when answers are delivered. Required checks: ./dc check full

Task page flags an ACP answer with no agent event for 1 min after hand-over; rounds say "Delivered when all rounds are answered" and Held/Sent. PR #6108 merged via lane; quick gate green. Round grouping deferred to draft #7649.