fix: render live V2X vehicles in Cesium preview

docs/v2x-cesium-preview.md

@@ -95,10 +95,12 @@ Unbound phases are counted in the panel — override them with `phaseSignalMap`.
 Vehicles follow the dashboard's rules: the push `interval` (`0` falls back to
 500 ms) sets the animation duration, a vehicle not updated within
 `interval * 1.5` is hidden, and hidden entries stay as reusable slots rather
-than being removed. Models are named as the dashboard names them —
-`car_obu.glb` for OBU vehicles and `${type}${subType}.glb` for recognized
-targets — falling back to the first packaged model, with the shortfall reported
-in the panel.
+than being removed. The OBU data hook calls its model `car_obu.glb`, but the
+dashboard's final `CrossCars` template renders `11.glb`; the preview uses that
+final rendering contract. Targets use `${type}${subType}.glb`. The dashboard
+vehicle assets are packaged under `_preview/v2x-vehicles/`. Valid live vehicles
+are lifted clear of the road, remain at least 28 screen pixels in overview, and
+the first live push focuses the camera near the vehicle group.
 
 ## Coordinate Contract
 
@@ -119,7 +121,8 @@ without Nginx, use the repository's proxy static server instead of
 `python3 -m http.server`:
 
 ```bash
-V2X_UPSTREAM=http://<v2x-api-host>:<port> \
+V2X_UPSTREAM=http://<v2x-api-host>:<port>/dashboardApi \
+V2X_WS_UPSTREAM=http://<v2x-ws-host>:<port>/dashboardWebsocket \
   npm run serve:v2x-preview -- --root outputs/fengshu-er-road --host 0.0.0.0 --port 7862
 ```