feat(web): subagent side panel with a live call-graph, compact chips in the stream (#78)

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

packages/docs/content/web-app.en.md

@@ -41,7 +41,7 @@ There are four approval modes: `allow-all`, `deny-all`, `read-only` (only read-o
 
 - Model text renders token by token; thinking blocks are collapsible;
 - Tool cards expand to show arguments and output, with a live timer while running;
-- Subagents appear as nested cards; context compaction shows a banner;
+- Subagents leave a full-width row in the stream, styled like the other collapsed step rows (agent avatar, name, short session id, running spinner, and an amber dot while one of their tool calls awaits approval); clicking it opens the agents side panel — a call graph of that row's Task on top (each node shows its elapsed time; click a node to switch) and the selected child's live conversation below — the child's own user prompts included — where nested tool cards and approvals work exactly as in the main chat. Panel visibility is task-scoped: sending a message that starts a new task closes it by default (entering a session starts closed too), and it comes back when you open it yourself or — on desktop — when the current task spawns a subagent (one auto-open per task; a manual close holds until the next task; never over an open files panel). Opening the panel from the toolbar, or switching sessions, shows the latest Task's graph; a row on an older turn brings back that turn's graph. The agents panel and the Workspace files panel never show together — opening one closes the other. Context compaction shows a banner;
 - After each Task, a stats line shows tokens, TPS, elapsed time, and cost.
 
 ### Input and Shortcuts

packages/docs/content/web-app.zh.md

@@ -41,7 +41,7 @@ penguin web
 
 - 模型文本逐 Token 渲染，思考块可折叠；
 - 工具卡片可展开查看参数与输出，执行中显示实时计时；
-- 子 Agent 以嵌套卡片呈现；上下文压缩以横幅提示；
+- 子 Agent 在消息流中只留下一条通栏行，样式与其他折叠步骤行一致（头像、名称、短会话号、运行中转圈，子会话内有待审批时带琥珀色圆点）；点击打开右侧智能体面板——上方是该行所属 Task 派生关系的调用图（节点上显示运行时长，点节点切换），下方是所选子会话的实时对话（含子会话自己的用户消息），嵌套工具卡片与审批与主对话完全一致；面板的显示以任务为界：发送消息开启新任务时默认关闭（进入会话时同样默认关闭），仅在手动打开、或（桌面端）当前任务派生子智能体时重新显示（每个任务自动打开一次，任务内手动关闭后保持关闭到下个任务，且不抢占已打开的工作区面板）；从工具条打开面板或切换 Session 时默认展示最新 Task 的调用图，点旧轮次的行则回看那一轮的调用图；智能体面板与工作区面板不会同时显示，打开一个即关闭另一个；上下文压缩以横幅提示；
 - 每个 Task 结束后显示统计行：Token 用量、TPS、耗时与费用。
 
 ### 输入与快捷操作