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.

GitHub Copilot CLI でインタラクティブな Windows セッションを開始し、issue に示されている PowerShell コマンドを使って permission-gate/tool-approval の確認プロンプトを再現します。レンダリングされたプレビューとコマンドの完全なテキストを比較し、絶対パスがどのように表示されるかに注目します。プレビューでドライブ文字全体とパスの各セグメントが切り詰められずに保持されれば完了です。