Remove deploy/demo and rewire benchmarks to the real compose stack

[bihius]

Summary

• Removed the obsolete deploy/demo stack and cleaned up its references.
• Updated benchmark lab startup to use deploy/docker/docker-compose.yml and the real Guard Proxy network.
• Kept lab setup working by seeding the admin through the backend and exposing the backend port only for the lab overlay.
• Refreshed testing and evaluation docs to point at the new workflow.

Testing

• Validated the merged Compose configuration with the benchmark overlay.
• Ran shell syntax checks on the updated lab scripts.
• Searched the repo for stale deploy/demo / guard-proxy-demo references and confirmed none remain.