fix(bridge): surface between-turn AskUserQuestion as its own card

[floodsung]

Summary

• AskUserQuestion works inside a user-initiated turn (the bridge sees state.pendingQuestion and renders a dedicated question card with a typed-reply prompt). Between turns — teammate / /goal / continuation-burst follow-up — the PreToolUse hook in PersistentClaudeExecutor fires with activeTurn === null, so there is no streaming CardState to piggy-back on.
• The question text only landed inside the coalesced "Agent activity" body, and the user's typed reply was treated as a fresh user turn — which then blocked for 6 minutes on the still-hanging hook (user-visible: "Thinking…" forever).
• This PR adds a between-turn-question event side-channel so the bridge can render a dedicated question card and route the user's next reply back through the existing executor.resolveQuestion() path.

What changed

src/engines/claude/persistent-executor.ts

• Extracted parseAskUserQuestionInput() (mirrors the parse logic in stream-processor.extractPendingQuestion) and exported a BetweenTurnQuestionEvent payload shape.
• In askUserQuestionHook, when this.activeTurn is null, emit between-turn-question after the resolver has been registered in pendingQuestionResolvers (so a fast bridge reply can't race past it). The hook still awaits as before — emission is purely a side-channel.

src/bridge/message-bridge.ts

• New pendingBetweenTurnQuestions: Map<chatId, { toolUseId, questions, cardMessageId }>.
• attachSpontaneousHandler subscribes to between-turn-question alongside the existing spontaneous / continuation-turn channels.
• handleBetweenTurnQuestion() sends a fresh question card via sendQuestionCard (fallback sendCard); single in-flight slot per chatId (older one is marked superseded). Multi-sub-question between-turn calls only surface the first question (rare; logged warning).
• tryHandleBetweenTurnQuestionReply() runs at the top of handleMessage (right after the /command early-return) — parses the typed reply, calls executor.resolveQuestion(), and updates the question card to a "complete" answered state. Falls back to error state if the executor is gone (e.g. evicted between question and reply).
• On executor-removed (LRU eviction / /reset), any pending between-turn question card is flushed to an error state so the user isn't left hanging.

tests/between-turn-question.test.ts

• 7 new tests covering parseAskUserQuestionInput (well-formed / malformed / non-object input) and the executor hook (emits when no activeTurn; does NOT emit when one exists; resolver registered before event; abort cleans up).

Test plan

Automated:

• npm run build — clean.
• npx vitest run — 298/298 pass (was 291, +7 new).
• npm run lint — 0 errors (pre-existing warnings unrelated to this change).

Manual:

• Start a chat with a teammate / /goal task that triggers AskUserQuestion between user turns.
• Confirm a dedicated question card appears (separate from the coalesced "Agent activity" card).
• Reply with the option number or free text — card flips to "✅ Reply: …" state; the agent's main work resumes within seconds (not 6 minutes).
• Trigger a second between-turn question without answering the first — the older card is marked "Superseded by a newer question." and the new card supersedes it.
• During a between-turn question, run /reset — question card flips to "Question canceled — agent session ended." and a subsequent user message starts a new turn cleanly.

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