app-server README thread/start example uses invalid sandbox value

What happened?

The app-server README's thread/start example uses:

"sandbox": "workspaceWrite"

But the generated SandboxMode schema allows the kebab-case values:

"read-only" | "workspace-write" | "danger-full-access"

The Rust enum is also serialized with rename_all = "kebab-case", so workspaceWrite does not appear to be a valid value for this field.

Expected behavior

The thread/start example should use a valid sandbox value such as "workspace-write".

Additional context

I searched open issues and PRs for terms including workspaceWrite, workspace-write, SandboxMode, thread/start, and app-server README, and did not find an existing open item that appears to cover this invalid example value.