Amazon Q Unable to Log In

## Problem
I am unable to use Amazon Q: when I try to login (either with free or pro license) I get the following output in the Amazon Q logs:
```
2025-05-21 16:21:18.289 [info] auth: Updating connection state of e4a77758-823f-40f3-aacc-db72c5f913c1 to authenticating
2025-05-21 16:21:18.289 [info] codewhisperer: connection changed to authenticating: e4a77758-823f-40f3-aacc-db72c5f913c1
2025-05-21 16:21:18.322 [info] current client registration id=undefined
expires at undefined
key = e4a77758-823f-40f3-aacc-db72c5f913c1
2025-05-21 16:21:20.265 [error] ssoSetup encountered an error: Error: Failed to connect to IAM Identity Center [FailedToConnect]
-> Error: [UriError]: Scheme contains illegal characters.
2025-05-21 16:21:20.265 [error] webviewId="aws.amazonq.AmazonCommonAuth": Error: Webview error
-> Error: Webview backend command failed: "startCodeWhispererEnterpriseSetup()"
-> Error: Failed to connect to IAM Identity Center [FailedToConnect]
-> Error: [UriError]: Scheme contains illegal characters.
```

## Steps to reproduce the issue
1. Uninstall Amazon Q
2. Install Amazon Q using Viceroy
3. Select sign-in option
4. See error (and failure to sign in)

## Expected behavior
I am able to login and continue using Amazon Q extension.

## System details (run `AWS: About` and/or `Amazon Q: About`)
```
OS: Linux x64 5.10.236-208.928.amzn2int.x86_64
Visual Studio Code extension host: 1.100.2
Amazon Q: 1.68.0
node: 20.19.0
```

Reproduce the sign-in failure by installing Amazon Q using Viceroy and selecting the sign-in option, then inspect the Amazon Q logs and the reported FailedToConnect and UriError messages. Done means a free or pro license can authenticate and the Amazon Q extension can be used without the webview error.

Written by the indexing model from the issue text.