fix(sky): keep the Sun and Moon, settle outside the ICRF tables

- Pass the custom sky box to the Viewer instead of `skyBox: false`, which
  also stopped CesiumWidget from creating the Sun and the Moon. Guarded by
  scripts/qa-sky-sun-moon.mjs.
- Outside the IAU 2006 tables (before 1975, after ~2050) the preload
  resolves without data; remember that span and stay on TEME instead of
  preloading and rendering every frame.
- The anime style no longer cel-shades the far plane, where four bands
  turned the faint Milky Way into blotches.
- Paint the planets out after the star-removing opening and with the
  ring median, so no brighter plateau is left; faces rebuilt.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

src/app/viewer.js

@@ -120,9 +120,10 @@ export function createApplicationViewer({ container, creditContainer }) {
     selectionIndicator: false,
     infoBox: false,
     baseLayer: false,
-    // Replaced below: the default Tycho-2 cube map is too coarse for the
-    // whole-globe view and its JPEG blocks show around the Earth.
-    skyBox: false,
+    // Instead of the default Tycho-2 cube map, whose JPEG blocks show around
+    // the whole globe. Passed here, not assigned later: `skyBox: false` would
+    // also stop CesiumWidget from creating the Sun and the Moon.
+    skyBox: new StarrySky(),
     creditContainer,
     msaaSamples: 4,
     contextOptions: { webgl: { preserveDrawingBuffer: true } },
@@ -134,7 +135,6 @@ export function createApplicationViewer({ container, creditContainer }) {
     // render loop. See app/atmosphereCompat.js.
     applyModelAtmosphereWorkaround(viewer.scene);
     viewer.scene.globe.show = false;
-    viewer.scene.skyBox = new StarrySky();
     viewer.scene.skyAtmosphere.show = true;
     viewer.scene.skyAtmosphere.atmosphereLightIntensity = 18;
     viewer.scene.skyAtmosphere.saturationShift = -0.12;