feat(compute): add SPICE WebSocket console support

Add WebSocket-based console support for SPICE protocol, enabling
   browser-based graphical console access with enhanced features
   like clipboard sharing, USB redirection, and audio streaming.

   Changes:
   - Add start_spice_websocket_console() method in BaseNode for SPICE
     WebSocket to TCP bridging with bidirectional binary forwarding
   - Add /console/spice WebSocket endpoints in QEMU and Docker compute APIs
   - Add /console/spice WebSocket proxy endpoint in controller API
   - Add comprehensive API documentation in docs/features/

   Supported console types:
   - spice: Basic SPICE protocol support
   - spice+agent: SPICE with spice-vdagent for enhanced features

   Architecture:
   - Browser WebSocket → Controller (JWT + RBAC) → Compute (Basic Auth)
   - No external websockify processes required
   - Consistent with existing VNC WebSocket implementation

gns3server/api/routes/compute/docker_nodes.py

@@ -399,6 +399,21 @@ async def vnc_console_ws(
         await node.start_vnc_websocket_console(websocket)
 
 
+@router.websocket(
+    "/{node_id}/console/spice"
+)
+async def spice_console_ws(
+        websocket: Union[None, WebSocket] = Depends(ws_compute_authentication),
+        node: DockerVM = Depends(dep_node)
+) -> None:
+    """
+    SPICE Console WebSocket.
+    """
+
+    if websocket:
+        await node.start_spice_websocket_console(websocket)
+
+
 @router.post(
     "/{node_id}/console/reset",
     status_code=status.HTTP_204_NO_CONTENT,