Permission-gate/tool-approval preview truncates full Windows paths

Describe the bug

When the CLI displays a permission-gate/tool-approval confirmation prompt before running a tool call (e.g., a PowerShell command referencing a file path), the rendered preview shows a truncated version of the path — dropping the leading drive letter and/or earlier path segments (e.g., showing \Users\UserName\ instead of the full C:\Users\UserName\Folder\SubFolder\...) — even though the actual command text passed to the tool contains the complete, correct absolute path.

Affected version

GitHub Copilot CLI 1.0.82

Steps to reproduce the behavior

1. Start an interactive session with GitHub Copilot CLI on Windows.
2. Ask the agent to run a PowerShell command that references a full absolute path, e.g.: Get-ChildItem "C:\Users\Username\Folder\SubFolder" -Force
3. When the permission-gate confirmation dialog appears (asking to approve the tool call), observe the path as rendered in that preview.
4. Compare against the actual command string — the underlying command is correct and full, but the displayed preview text is partial/truncated.

Expected behavior

The permission-gate preview should render the full, untruncated absolute path exactly as it appears in the command being executed, with no segments dropped.

Additional context

• CLI version: 1.0.82
• OS: Windows
• This is purely a display/rendering issue in the confirmation UI — the command itself executes against the correct full path when approved. Reproduced consistently across multiple tool-call approvals across multiple sessions.

在 GitHub Copilot CLI 中启动交互式 Windows 会话，并使用 issue 中显示的 PowerShell 命令重现 permission-gate/tool-approval 确认提示。将渲染后的预览与完整的命令文本进行比较，重点关注绝对路径的显示方式。当预览完整保留驱动器号和所有路径段且未被截断时，即视为完成。