[EugeneTheDev]

Problem

Codex's request_user_input_async tool asks questions without waiting: it emits an agentMessage with delivery: "async" and questions, and the turn continues. The adapter dropped these messages, so Air showed nothing and the agent went on with its defaults (IJAI-4999).

Fix

• Show agent messages that arrive whole, without deltas, so the question text appears live.
• Send async questions as a non-blocking form elicitation. On ACP v2 the session state stays running while the form is open.
• Steer an accepted answer into the turn that asked, in the reply envelope Codex clients use. Declining or cancelling sends nothing.
• Cancel open elicitations with $/cancel_request when their turn ends, the session closes or the app-server is lost.
• Drop an answer that arrives after its turn ended, as the Codex TUI does, and send a warning notice where the client supports notices.
• On replay, show a stored answer as the quoted question followed by the answer, instead of the raw envelope.

Behaviour is documented in docs/async-questions.md. Tests cover ACP v1 and v2.