feat(cli): bgagent ask Phase 2 (POST /tasks/{id}/asks)

**Context:** ROADMAP.md → `bgagent ask` (Phase 2)

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## Component

Scripts / CLI

## Describe the feature

Mid-run **questions to the agent**: `POST /tasks/{id}/asks`; answers durable as `status_response` events. CLI `bgagent ask ""` with foreground block-and-poll. Enables interactive summaries without burning a separate status API.

## Use case

Operators need "why did you change X?" mid-flight without `nudge`ing implementation guidance. Answers must survive CLI disconnect.

## Proposed solution

1. REST: create ask, poll events by `correlation_id=ask_id`.
2. Agent between-turns hook injects ask as user turn; emits `status_response`.
3. CLI spinner + adaptive poll; `bgagent asks show ` for reconnect.
4. Sync `cli/src/types.ts` with `cdk/.../types.ts`.
5. Fanout Slack renderer for `status_response` (Phase 2).

## Other information

- Full spec: `docs/design/INTERACTIVE_AGENTS.md` §5.5, AD-6/AD-7.
- `status_response` already in fanout allowlist (forward-compat).

- [ ] This might be a breaking change

Leggi prima docs/design/INTERACTIVE_AGENTS.md §5.5 e AD-6/AD-7, quindi esamina le definizioni dei tipi CLI e CDK in cli/src/types.ts e cdk/.../types.ts. Traccia il flusso REST ask, l’hook between-turn, il polling degli eventi, il comando reconnect e il fanout Slack status_response descritti nella proposta. Il lavoro è completo quando il comportamento della Fase 2 e i tipi sincronizzati coprono tutti i percorsi elencati.

Scritto dal modello di indicizzazione a partire dal testo della issue.