x/elevate is now a generic client: reads OLLIE_ELEVATE_SOCKET, sends
{cmd,cwd}, reads back {stdout,stderr,exit_code}. All backend-specific
logic moves to adapters. Add elevate-adapter-superpowerd as the
reference adapter: owns the socket lifecycle, translates the ollie
protocol to superpowerd JSON-RPC ExecuteCommand. Add OLLIE_ELEVATE_SOCKET
to env docs. Update scripts/README.md with protocol spec, adapter
setup, and guide for writing custom adapters.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>