Kata sandbox demo

Control side (namespace kata-control):

• /api/sandboxes → Quarkus sandbox manager (needs the X-Api-Key header)
• /dashboard/?key=… → live dashboard, /chat/ → CopilotKit chat

Sandbox side (namespaces kata-router, kata-sandboxes):

• /sandbox/<id>/ → that sandbox's Kata microVM, only with an access token issued by the manager

See the project README for the curl commands.