Task 615: Fix 3D Viewer Ship Marker Visibility Across All Scene Types

Status: DONE

Problem

The ship marker in the 3D orbital viewer was invisible in all scene types:

• Screenshots at different timeline positions looked identical — no visible ship movement
• Root cause investigation revealed the ship WAS rendering and animating correctly, but:

1. Ship marker was too small to see at camera distances (0.2 radius in scenes spanning 5-100 scene units)

2. Ship color was overridden to match the transfer arc color (episode color), making it blend in

Solution

1. Increased ship marker sizes for all scene types:

- Full-route: 0.2 → 0.4 (visible against planet scale)

- Episode scenes: 0.6 → 0.8 (clearly visible)

- Local encounter scenes: 0.2 → 0.15 (proportional to moons)

1. Kept ship white instead of recoloring by episode — white contrasts against all arc colors and dark background
2. Added CSS2D label "▲ ケストレル" above ship marker for identification
3. Added 5 TDD tests verifying all scenes provide correct timeline data for ship animation

Files Modified

• ts/src/orbital-3d-viewer.js — ship marker size, color, label creation, label sync in update loop
• ts/src/orbital-3d-viewer-data.test.ts — 5 new tests for ship animation data completeness