'!Failed to load N skills' error even though all skills are disabled.

### Describe the bug

I have disabled all skills. When I open a new copilot session from Windows Terminal, I see '!Failed to load N skills' error even though all skills are disabled.

### Affected version

GitHub Copilot CLI v1.0.67

### Steps to reproduce the behavior

1. Type copilot in Windows Terminal
2. Press Enter
3. Disable all skills
4. Exit copilot
5. Type copilot
6. Press Enter
7. View error message

### Expected behavior

Zero error messages appear when starting a copilot session from Windows Terminal with all skills disabled.

### Additional context

_No response_

首先，從 Windows Terminal 中的 Copilot 入口點重現此問題：停用所有 skills，退出，然後啟動新的工作階段。追蹤「!Failed to load N skills」訊息的啟動處理，並確認在停用所有 skill 的情況下重新啟動不會產生任何錯誤訊息。

由索引模型根據 Issue 內容生成。