Remove all SPICE WebSocket-related code due to frontend dependency issues
with spice-html5 library (missing RSAKey/BigInteger implementations).
Changes:
- Remove start_spice_websocket_console() from BaseNode
- Remove SPICE WebSocket endpoints from QEMU and Docker compute APIs
- Remove SPICE WebSocket proxy endpoint from controller API
- Remove WebSocket subprotocol handling from authentication layers
- Remove SPICE documentation
The SPICE console type remains functional for direct connections,
but WebSocket proxy support has been removed.
Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>