Remote control task URL returns 404 even though local session completes

### Short summary

Opening the remote control task URL from the GitHub Copilot desktop app returns a GitHub 404 page, even though the local app shows that remote control is enabled and the task completes successfully.

### Affected version or release

v1.0.10

### Installation context

Windows

### What happened?

When attempting to open a remote control task from the GitHub Copilot desktop app, the browser navigates to a GitHub URL (https://github.com/copilot/tasks/), but instead of displaying the task or session, it returns a 404 error page. Despite this, the local application indicates that remote control is enabled and the task itself runs successfully, suggesting that the issue is specifically with accessing or resolving the remote task URL.

### Steps to reproduce

1. Open the GitHub Copilot desktop app on Windows.
2. Change New sessions remote access from View only to Remote control.
3. Start a new session.
4. Run a simple remote control test task.
5. Click Open on remote.
6. The browser opens a URL similar to:
> https://github.com/copilot/tasks/
7. The GitHub page returns:
8. 404 - This is not the web page you are looking for

### Expected behavior

The github.com/copilot/tasks/ page should open the corresponding remote control task/session, or the app should show a clear error if the task URL is not available for this account/session.

### Actual behavior

The local app reports that Remote Control is enabled and the task itself completes successfully. In my test, the task showed:
> Worked for 42s, 2 tools, 1 message

Output confirmed the session could run remote commands as the local user

### Additional context

This does not look like the local remote-control execution failed. The local task completes successfully, and the failure appears to be specifically around opening or resolving the generated GitHub task URL.

Related but not identical: #1289 reported remote control being unavailable with an RPC error. In this case, remote control appears enabled locally, but the generated copilot/tasks/ URL is not accessible.

No repository file or test is identified in the report. Reproduce the issue on Windows with app v1.0.10 by enabling Remote control, completing a task, and selecting Open on remote; inspect the generated github.com/copilot/tasks/ URL. Done means the task opens successfully or the app presents a clear error when the session is unavailable.

索引モデルが issue の本文から書いたものです。