Can not authorize MCP server using Oauth

### Describe the bug

I'm trying to add sentry MCP server to copilot but it stuck on authentication step.

### Affected version

GitHub Copilot CLI 1.0.49

### Steps to reproduce the behavior

1. Add sentry MCP server to ~/.copilot/mcp-config.json
```
"sentry": {
"url": "https://mcp.sentry.dev/mcp"
}
```
2. start copilot cli and run `/mcp auth sentry`

### Expected behavior

It shows a url to open and authorize on the web

### Actual result

It show this and stuck until timed out

```
Authenticating: sentry

◎ Waiting for authorization in browser...
```

### Additional context

The CLI is running on a remove server and I accessed via SSH, so opening in a browser should not be expected

Start with the `/mcp auth sentry` entry point and the MCP configuration shown in `~/.copilot/mcp-config.json`. Reproduce the flow over SSH using the Sentry server URL, then trace where browser authorization is awaited. Done means remote users can complete or continue OAuth without requiring a browser on the CLI host.

Written by the indexing model from the issue text.