Registers cpu, memory, cpu_telemetry, array_state, parity_progress,
ups_status, notifications_overview, owner, and server_status as MCP
resources under unraid://live/{action}. Each opens a transient WebSocket
via subscribe_once() and returns JSON; exceptions degrade gracefully to
an error JSON dict rather than raising. Skips log_tail and
notification_feed (require params, not suitable as resources).
