Plan-approval card and "?" session indicator remain during a sub-session's post-approval work when the plan was approved from the parent chat

### Short summary

Plan-approval card and "?" session indicator remain during a sub-session's post-approval work when the plan was approved from the parent chat.

### Affected version or release

Desktop app, July 2026 build (agent/CLI version reported as 1.0.71 — exact desktop app build unknown).

### Installation context

GitHub Copilot desktop app on Windows; single project with 2–4 parallel sub-sessions orchestrated from one parent chat.

### What happened?

In a parent chat I orchestrate multiple sub-sessions. When a sub-session pauses in plan mode, I approve its plan *from the parent chat* (via the assistant, not by opening the sub-session). The approval registers and the sub-session begins implementing in autopilot. However, while it is working: (1) the plan card in the sub-session transcript still renders the "Approve and implement / Exit plan mode / Suggest changes" options as if pending; (2) the sidebar keeps the "?" (awaiting input) icon on that session. When the sub-session finishes, the "?" icon changes to the blue "done" dot and the card disappears — so the stale state is transient, lasting only for the duration of the post-approval work. It is most visible on longer tasks; a quick read-only task finishes too fast to notice. The issue: I have already approved, so the session should not present an awaiting-input state at all during work — it looks like it is still blocked on me when it isn't.

### Steps to reproduce

1. From a parent chat, spin up a sub-session in plan mode.
2. Wait for it to produce a plan and pause for approval.
3. Approve the plan from the parent chat (not by opening the sub-session).
4. While the sub-session works, observe it: the approval card + "?" icon remain as if awaiting me. Use a task long enough to run for a while — quick tasks finish before the stale state is easy to see. Both clear when the sub-session completes.

### Expected behavior

Once a plan is approved (from anywhere, including the parent chat), the sub-session should immediately reflect a "running/approved" state — the approval card should collapse to a non-actionable "approved" state and the "?" awaiting-input indicator should switch to the working/done indicator right away, not only when the work finishes.

### Additional context

Orchestrating 2–4 parallel sub-sessions in one project; approvals issued from the parent chat. Screenshot attached showing an "Approved plan" event with the still-rendered approval card in the same sub-session transcript.

在桌面应用中，从父级聊天中批准一个计划，并在批准后的较长任务期间观察子会话，以复现该问题。检查批准前后子会话的转录内容和侧边栏状态；当批准卡片不再可操作，并且等待输入指示器立即变为工作状态（在完成之前）时，即视为完成。

由索引模型根据 Issue 内容生成。