Queued prompts occasionally remain stuck after the session becomes idle

先在互動式 Copilot CLI 工作階段中，於使用中的工作執行時按下 Ctrl+Q 來重現問題，接著檢查佇列管理器以及轉換至閒置工作階段的流程。確認工作階段變為閒置後，佇列中的提示會自動傳送，且佇列管理器會在需要時提供「Send now」的備援選項。

Describe the bug

Queued prompts are not dequeued consistently. Occasionally, after pressing Ctrl+Q to enqueue a prompt while Copilot CLI is busy, the prompt remains listed under Queued (1) Ctrl+Q to manage even after the session becomes idle.

The queue manager allows the queued prompt to be edited or deleted, but it does not provide a "Send now" action, and the prompt never dispatches automatically. Deleting the queued prompt and submitting the same text manually works.

Affected version

1.0.83-3

Steps to reproduce the behavior

1. Start an interactive Copilot CLI session and submit a prompt that keeps the session busy.
2. While it is busy, type another prompt and press Ctrl+Q to enqueue it.
3. Wait for the active work to finish and for the session to become idle.
4. Observe that, intermittently, the status continues to show Queued (1) Ctrl+Q to manage and the prompt is never sent.
5. Press Ctrl+Q to manage the queue. The prompt can be edited or deleted, but there is no option to send it immediately.
6. Delete the queued prompt and submit the same text manually; it sends successfully.

This is intermittent and does not happen for every queued prompt.

Expected behavior

A queued prompt should automatically dispatch when the session becomes idle. The queue manager should also provide a "Send now" action as a fallback when automatic dequeueing does not occur.

Additional context

• Operating system: Windows
• Reproducibility: Intermittent
• UI remains responsive; queued prompts can still be edited or deleted.
• Manually resubmitting the same prompt succeeds.