Add AskUserQuestion hook

[novarii]

Summary

• Wires a PreToolUse hook matched to AskUserQuestion so Claude pausing to ask the user a question triggers a Warp notification.
• Reuses the existing question_asked event already defined in Warp's CLI agent protocol (CLIAgentEventType::QuestionAsked, mapped to Blocked status in cli_agent_sessions/mod.rs) — no Warp-side change needed.
• New script follows the same pattern as on-permission-request.sh: extracts the first question's text as summary, truncates to 200 chars, sends via warp-notify.sh.

Motivation

AskUserQuestion is one of the most frequent ways Claude blocks waiting for the user, but it currently produces no Warp notification. Users running Claude in the background miss prompts entirely unless they're already focused on the Warp pane. The Warp side has supported the question_asked event since v1 of the protocol — the plugin just hasn't been emitting it.

Test plan

• tests/test-hooks.sh passes (40/40, including new silent-exit assertion for the script)
• Manual payload inspection — build_payload produces:

  {"v":1,"agent":"claude","event":"question_asked","session_id":"abc","cwd":"/tmp/foo","project":"foo","summary":"Which option do you prefer?"}

  which matches the shape v1::parse expects in event/v1.rs.
• End-to-end test in Warp (would appreciate a maintainer running this — I can confirm payload + OSC emission but can't reproduce the full Warp UI loop locally).