Fix Fuel URI in new_dvl world

[yeseorizi]

Summary

Fix the Fuel model URI used by new_dvl.world for the virtual North-East-Down frame.

The world referenced North-East-Down frame, but the published Fuel model is named North East Down frame. The malformed URI returns HTTP 404 and Gazebo reports Error Code 14, preventing the world from loading normally.

Change

- https://fuel.gazebosim.org/1.0/hmoyen/models/North-East-Down frame
+ https://fuel.gazebosim.org/1.0/hmoyen/models/North East Down frame

This also makes new_dvl.world consistent with the other DAVE worlds that use the same model.

Reproduction

curl -L -o /dev/null -sS -w '%{http_code}\n' \
  'https://fuel.gazebosim.org/1.0/hmoyen/models/North-East-Down%20frame'
# 404

A Gazebo launch with the original world reports:

Failed to download model.
REST response code: 404
Error Code 14: Unable to find uri[.../North-East-Down frame]

Validation

curl -L -o /dev/null -sS -w '%{http_code}\n' \
  'https://fuel.gazebosim.org/1.0/hmoyen/models/North%20East%20Down%20frame'
# 200

xmllint --noout models/dave_worlds/worlds/new_dvl.world
pre-commit run --files models/dave_worlds/worlds/new_dvl.world

The corrected world was also launched in an ARM64 Docker environment with ROS 2 Lyrical and Gazebo Jetty:

ros2 launch dave_demos dave_sensor.launch.py \
  namespace:=dvl world_name:=new_dvl paused:=false \
  gui:=true headless:=false

Observed after the change:

• world create request completed successfully
• Gazebo /dvl/velocity payload received
• ROS /dvl/velocity payload received
• simulation iterations advanced
• no Fuel URI or fatal signature was observed

Checklist

• The change is limited to one issue.
• XML validation passed.
• Repository pre-commit hooks passed for the changed file.
• The corrected Fuel resource was verified and the world was re-run.