Bell does not work anymore even with `"bell": true` in the settings

### Describe the bug

In version 1.0.55, the bell character doesn't seem to be sent (I don't get the urgent window hint anymore) even when having `"bell": true` in the settings.

### Affected version

GitHub Copilot CLI 1.0.55.

### Steps to reproduce the behavior

1. Write any prompt
2. Wait for the LLM to finish the task

### Expected behavior

The urgent window hint should be set

### Additional context

Operating system: Linux
Arch: x86-64
Terminal: Alacritty
Shell: Fish

Reproduce the issue using GitHub Copilot CLI 1.0.55 on Linux x86-64 in Alacritty with Fish and `"bell": true`, then trace the bell handling after an LLM task finishes. Done means the terminal emits the bell character and the urgent window hint appears as expected.

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