#1068 Retire Highway copilot (copilot.highway.rodmena.app code completion)

EARS SPEC: - When a client requests copilot.highway.rodmena.app after retirement, the edge shall answer 410 Gone (infra). - The dashboard shall send no request to copilot.highway.rodmena.app, and its served bundle shall not reference it (dashboard team). DECISION: director, 2026-10-25 ('yes to all' on the copilot retirement recommendation). The backend has been absent since at least 2026-08-14: no unit, no process on 127.0.0.1:7388, and /home/farshid/develop/highway-copilot is gone. Highway's own repo has no copilot reference (grep of api, enterprise, engine, config and compose).