feat(web): implement conversation timeline and execution controls

> 本轮按 [M1 汇合计划](https://github.com/AgoraIO-Extensions/agent-infra/issues/150) 补充执行详情消费契约。保留 LichKing-2234 的既有主责及人工/本地受监督实现方式；新增契约待评估，Project 保持 Todo。实现前须完成适用文档评审与合入、依赖回读和本票执行准入；本次修订不代表开始开发。

## Problem

The Pilot needs a durable ChatGPT-style text experience that can submit Codex work, stream persisted events, recover from disconnects, control executions, and show GitHub results without exposing internal or cross-user data.

## Scope

- Implement Agent conversation entry, new/history navigation, text composer, model/reasoning selection, timeline, execution detail, and PR link/result summary.
- Implement SSE connection, event deduplication, cursor replay, reload signals, offline/reconnecting states, and persisted-history merge.
- Implement stop, supplemental instruction, regenerate, busy, retry, permission-lost, session-unavailable, and terminal states.
- Use generated contracts and schema-derived Mocks; do not implement file upload/download in Pilot.
- Ensure user/Owner projections cannot reveal other users' conversations, attachments, Runtime IDs, grants, or credentials.
- Add responsive component and browser consumer tests.

- 消费 [持久任务契约](https://github.com/AgoraIO-Extensions/agent-infra/issues/482) 与 [实际模型/工具事实](https://github.com/AgoraIO-Extensions/agent-infra/issues/483) 的同一公共 Schema、生成 Client 和受控业务事件，补齐本主体执行详情的受理、等待、执行、结果及失败原因。按实际操作/尝试显示开始、终态、已确认耗时和可得用量；缺失、未知、不支持分别显示，不用总任务耗时或模型自报内容代替调用事实。
- 等待、取消处理中、确认停止、等待到期和待核实均按服务端结果展示；保留现有 Web 补充指令/繁忙/重生成规则，不将新 Turn 插入已受理任务之前。重连、游标重放和重新加载不重复事件或尝试，也不自动重提有副作用的任务。
- 详情与已有输出按原任务主体和当前权限读取；应用责任人/Owner 不自动获得应用或其他用户的任务列表、结果和取消权。技术组件/主机定位留在运维后端；Connection 只展示获准且经核实的关联引用，外部效果在独立授权入口查询。[审计管理页](https://github.com/AgoraIO-Extensions/agent-infra/issues/484) 与 [评测和主动反馈](https://github.com/AgoraIO-Extensions/agent-infra/issues/485) 分别由原票交付；本票不生产 Runtime 事实、不实现任务调度或复制 Connection 记录。

## Acceptance criteria

- [ ] **AC-1:** Text submission and timeline render submitted/processing/streaming/terminal states without duplicate events across reconnect/reload.
- [ ] **AC-2:** Stop, supplemental, regenerate, busy, retry, permission loss, and unavailable states follow contract and never rebind a command to another Execution.
- [ ] **AC-3:** History and execution details enforce user-scoped projections and display trace/call/PR summaries without internal secrets or model thought.
- [ ] **AC-4:** Model/reasoning selection applies from the next message and handles removed/invalid options explicitly.
- [ ] **AC-5:** Desktop/mobile tests cover reconnect, reload-window expiry, cross-user denial, and long output without layout overlap.

- [ ] **AC-6:** 真实持久业务事件驱动的页面能串起受理、等待、执行、模型/工具和结果阶段，展示已确认耗时、状态、失败原因和可得用量；四模板消费同一 Schema，缺失/未知/不支持不填成成功或零值，合法新尝试与重放可区分。
- [ ] **AC-7:** 等待、取消处理中、确认停止、待核实及恢复均与原 Execution 一致；游标重放/重载不重复内容或触发任务，Web 补充指令/繁忙/重生成行为保持。查询错误明确呈现，不伪装空历史或成功。
- [ ] **AC-8:** 浏览器真实消费流程证明本主体权限、凭证失效/主体撤权后的访问收缩；Owner/责任人和资源 ID/游标替换不能越权。应用任务不自动对责任人可见，Connection 关联不泄漏外部对象存在性或绕过独立授权，业务正文不进入遥测。

## Validation

- Run focused Web reducer, SSE, generated-client, Mock scenario, accessibility, responsive, and consumer tests.
- Run the complete repository validation sequence in `AGENTS.md`.

- 先用公共 Schema fixture 验证页面状态，再接正式 API/Store/Worker/RuntimeHost 读取真实任务和调用事实；回读成功、等待、模型/工具失败、取消确认、unknown、断线/重载及四模板消费结果，Mock 或截图不能单独证明真实链路。
- 以两用户及独立应用验证任务/游标替换、Owner/责任人越权、凭证失效及主体撤权，保留本票既有移动端、无障碍和长输出回归；Connection 联合真实授权及外部操作验收仍由原 Pilot 入口交付。

## Blocked by

- #253
- #251
- #321
- #389
- #400
- #482
- #483

## Authority

- 本次新增范围按 [平台 PRD 候选 §§13–16](https://github.com/AgoraIO-Extensions/agent-infra/blob/2eb2762b889a27372c259039d27279cf646c5b1e/docs/prd/PRD-agent-platform-M1.md)、[工程 Spec 候选 §§18–19](https://github.com/AgoraIO-Extensions/agent-infra/blob/7f3b2083d44191ab4b280d7eb8222d7785937b8e/docs/architecture/SPEC-agent-infra-M1-engineering-architecture.md) 和 [Runtime HLD 候选](https://github.com/AgoraIO-Extensions/agent-infra/blob/5da6fff274ffc7a7ee36ae3ebd61d6100ccc9571/docs/architecture/HLD-agent-runtime-M1.md) 评审；实施前回读合入后的权威版本并复核差额，历史基础引用不能覆盖新增结论。