feat(runtime-host): expose agent graph client operations

[M4n5ter]

English

Summary

• Expose bounded agent.graph.query, agent.graph.operator.query, and agent.graph.stop operations through Runtime Host while keeping durable Graph state in its existing Runtime authority.
• Publish subscription.agent_graph_changed on the root Session subscription sequence so clients can invalidate and reload their projection without treating process-local notifications as replay state.
• Keep Graph lifetime independent from client connections: disconnecting does not stop execution, while an explicit stop is shared by every client observing the Session.
• Enforce strict recursive wire decoding, stable failure codes, omission accounting, result byte limits, and terminal-history continuation without changing the experimental v0 wire version.
• Document the client contract and cover projection bounds, protocol rejection, continuity ordering, and a two-client UDS query/disconnect/reconnect/stop flow.

Validation

• npm test
• npm run build
• npm run typecheck
• npm run lint
• npm run format:check

Part of #1167. Related to #853.

中文

概要

• 通过 Runtime Host 暴露有界的 agent.graph.query、agent.graph.operator.query 与 agent.graph.stop operation，同时让持久化 Graph state 继续由现有 Runtime authority 持有。
• 在 root Session subscription 的统一 sequence 上发布 subscription.agent_graph_changed，使客户端能够失效并重新加载 projection，而不会把进程内通知误当成 replay state。
• Graph 生命周期与客户端连接解耦：断开连接不会停止执行；显式 stop 则会由所有正在观察该 Session 的客户端共同看到。
• 强制严格的递归 wire decoding、稳定错误码、omission accounting、结果字节上限与 terminal-history continuation，并保持实验性 wire protocol 为 v0。
• 补充客户端契约文档，并覆盖 projection 边界、协议拒绝、continuity 排序，以及双客户端 UDS query/disconnect/reconnect/stop 流程。

验证

• npm test
• npm run build
• npm run typecheck
• npm run lint
• npm run format:check

属于 #1167 的一部分，关联 #853。