New entry cmd/xui-agent links only the agent dependency closure
(internal/agent + config/logger/selfupdate/xray/util leaves), a
drop-in replacement for the dual-mode binary's agent subcommand:
same invocation (xui-agent agent -config ...), same agent.json and
state files, same wire protocol.
selfupdate gains AgentAssetName (x-ui-agent-linux-<arch>); the
agent's one-click update now downloads the agent asset instead of
the panel binary. Pre-split agents keep fetching the panel asset —
the two forms are interchangeable at the install path.
Muse