Reads /etc/hyperhive/gui.json at startup to get the VNC port written
by the weston-vnc ExecStart script (issue #50). Adds:
- gui_vnc_port: Option<u16> on AppState
- gui_enabled: bool on StateSnapshot (for issue #52 screen link)
- GET /screen: serves a minimal RFB-over-WebSocket viewer (screen.html)
- GET /screen/ws: upgrades to WebSocket and byte-pumps to 127.0.0.1:<vnc_port>
The relay is a pure two-task byte pump (WS→TCP and TCP→WS), transparent
to any RFB variant including VeNCrypt. Returns 404 when gui is not
enabled.
screen.html is a self-contained RFB client: handshake, FramebufferUpdate
(Raw encoding), pointer and keyboard forwarding — enough to display the
desktop and interact with it. noVNC assets (issue #52) replace this.
Closes#51
