Fix CLI follow-up routing after completion asks

[cte]

Summary

• route stdin message to askResponse: "messageResponse" when CLI is waiting on an active ask (including completion_result)
• keep queue behavior for non-ask states
• add unit coverage for ask-response routing helper
• add integration case for completion-ask follow-up routing (responded path)
• relax brittle content assertion in existing follow-up streaming integration test to validate transport invariants

Why

This fixes the regression where a follow-up message sent after attempt_completion could be packaged as tool_result and ignored instead of appearing as a normal user turn.

Validation

• pnpm exec vitest run src/commands/cli/__tests__/parse-stdin-command.test.ts
• pnpm exec tsx scripts/integration/cases/followup-completion-ask-response.ts
• pnpm test:integration (10/10 passed)