Improve plan mode question flow

[germanescobar]

Summary

Improve the plan mode UX for Codex, and verify whether the same behavior applies to Claude Code. The current question/plan flow should make answered questions less noisy, support open-ended answers, and let the user approve implementation later without losing the ability to continue discussing the plan.

Desired behavior

• Collapse each question card after it has been responded to.
• Add an open/free-form answer option to each question, in addition to any structured choices.
• Add an always-visible Implement this plan button at the end of the plan flow.

Interaction details

• After answering a question, the card should collapse into a compact answered state so the conversation stays readable.
• The user should be able to keep chatting/refining after questions are answered.
• The Implement this plan button should remain available so the user can approve implementation only when ready.
• Clicking Implement this plan should send the appropriate approval/resume signal for Codex plan mode.

Notes

• This is specifically observed with Codex plan mode.
• Check whether Claude Code has the same question-card behavior and whether the same UI affordance should apply there.

Acceptance criteria

• Answered question cards collapse but remain inspectable/reopenable.
• Every question supports an open-ended answer path.
• Implement this plan is visible after a plan is available, even if the user continues the conversation.
• Codex receives the expected approval message/action when the user clicks Implement this plan.
• Claude Code behavior is checked and either supported or documented as not applicable.