feat(runtime-host): admit approved guest Turn requests

[M4n5ter]

English

Summary

Add durable exact Turn access requests. A Guest requests one immutable turn.start intent; the Owner decides it with revision fencing, and only an approved intent enters the canonical Turn admission path. Recovery schedules approved requests without delaying Host readiness, while idle-wait failures drain and leave the request recoverable.

Refs #3843

Verification

• npm run build:test
• node --test packages/runtime-host/dist/__tests__/session-collaboration-authority.test.js
• npm run lint
• npm run format:check

AI use

• No generative tool made a substantive contribution
• Generative tooling made a substantive contribution

Tool(s) and scope: OpenAI Codex implemented and verified the change under the maintainer's direction and review.

Checklist

• Tests cover the change and fail without it
• Lint, format, typecheck and the affected suites pass locally

Does this PR entail a change in behavior?

• Yes — described under Summary above
• No

中文

摘要

加入持久化的精确 Turn access request。Guest 请求一个不可变的 turn.start intent；Owner 通过 revision fence 决策，只有获批 intent 才进入 canonical Turn 准入路径。恢复过程不会因已批准请求而延迟 Host ready；等待 Session idle 失败时会进入 drain，并保留请求以供恢复。

关联 #3843

验证

• npm run build:test
• node --test packages/runtime-host/dist/__tests__/session-collaboration-authority.test.js
• npm run lint
• npm run format:check

AI 使用

OpenAI Codex 在维护者的指导和审核下参与了实现与验证。