Task 572: Add orbit ring labels in full-route view

Status: DONE

Summary

Added Japanese labels to orbit circles in the full-route 3D view (火星軌道,

木星軌道, 土星軌道, 天王星軌道, 地球軌道). Labels appear at the top of each

orbit ring, helping identify which ring belongs to which planet — especially

useful when planets animate away from their initial positions.

Files changed

• ts/src/orbital-3d-viewer.js — orbit circle labels (name param + createLabel)

Impact

• UX improvement: orbit rings now identifiable independent of planet positions