Remove the 'onFirstMessage' hack where backend sent VNC password as
first text WebSocket message and frontend passed the already-open WS
to noVNC's RFBClass. This caused RFB handshake failures because noVNC
couldn't properly manage a WebSocket it didn't create.
Changes:
- Backend: remove send_text(password) before proxy start
- Backend: improve proxy error logging from debug to info level
- Frontend (virtual_machines.html, instance_detail.html): pass WebSocket
URL string to RFBClass constructor - noVNC creates and manages its own
WebSocket connection, allowing proper RFB protocol handshake