copilot --resume hangs at Resuming session on cold start in Windows

### Describe the bug

On Windows, running `copilot --resume` directly from PowerShell starts the Copilot CLI TUI but remains indefinitely at `Resuming session...`. The resumed session never becomes interactive and no visible error is displayed.

The same sessions can be resumed successfully by first starting `copilot` normally and then running `/resume` from inside the active CLI. This appears specific to the cold-start command-line resume path.

### Affected version

```text
GitHub Copilot CLI 1.0.72-0
```

Installed through WinGet.

### Steps to reproduce the behavior

1. Have at least one existing Copilot CLI session available to resume.
2. Exit Copilot CLI completely.
3. From PowerShell, run `copilot --resume`.
4. Select a session if the session picker is displayed.
5. Observe that the TUI remains at `Resuming session...` and never becomes usable.
6. Terminate the hung process.
7. Run `copilot` without the resume flag.
8. From inside the running CLI, use `/resume` and select the same session.
9. Observe that the session resumes successfully.

### Expected behavior

`copilot --resume` should resume the selected session and become interactive, matching the behavior of `/resume` inside an already-running CLI.

### Additional context

- OS: Microsoft Windows 11 Enterprise, version 10.0.26200, build 26200
- CPU architecture: x86_64
- Terminal: Windows Terminal
- Shell: PowerShell 7.4.17
- No visible error is shown. The status line remains at `Resuming session...` indefinitely.
- Possibly related to #3458, which reported a previous Windows cold-start resume failure. That issue exited silently on version 1.0.51, whereas version 1.0.72-0 reaches the TUI and then hangs.

Reproduziere den Kaltstartpfad aus PowerShell mit `copilot --resume` und vergleiche ihn anschließend damit, `copilot` zu starten und innerhalb der CLI `/resume` zu verwenden. Untersuche den Resume-Ablauf, der sich zwischen diesen Einstiegspunkten unterscheidet; abgeschlossen ist die Aufgabe, wenn die ausgewählte Sitzung interaktiv wird, statt bei `Resuming session...` stehen zu bleiben.

Vom Indexierungsmodell aus dem Issue-Text verfasst.