Unable to sign in after login has expired

Normally Amazon Q logs me out after ~8 hrs of activity.

I was able to login successfully this morning

I tried logging in again (this evening) with `:AmazonQ login` and got the following error:
```
Amazon Q: {
code = -32603,
message = "Request workspace/executeCommand failed with message: UnknownError"
}
```

I was able to login to the cli just fine so doesn't seem to be an issue with my account.

Note: I am logging into a pro plan

**Environment Details**
nvim v0.11.4
Node 24.6.0
Macbook Pro
Chip Apple M2 Pro
OS: Sequoia 15.6.1

Start by reproducing the failure with the `:AmazonQ login` command after the login session expires, using the reported Neovim, Node, macOS, and Amazon Q Pro environment. Trace the plugin's login flow around the `workspace/executeCommand` error and verify that re-authentication succeeds without the `-32603 UnknownError` response.

Written by the indexing model from the issue text.