Build a body still waiting for its surface with a null map, so three stops warning on each one

Since de34fff paints derived surfaces after the system is built, every body without a photograph
was given map: undefined, and three's Material.setValues warns "parameter 'map' has value of
undefined" for each: eleven warnings every time the Sun's system was entered, one per exoplanet in
any other. The marker now starts with map: null, which three takes without a word and which
the deferred paint replaces as before. In the running app, entering the Sun (38 members) now logs
no console message at all.

Control: undefined again fails "builds a body still waiting for its surface without three warning
of an undefined map".

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

src/app/features/galaxy-system/system-orbits-renderer.spec.ts

@@ -1,5 +1,5 @@
 import * as THREE from 'three/webgpu';
-import { describe, expect, it } from 'vitest';
+import { describe, expect, it, vi } from 'vitest';
 
 import { DEFAULT_EPOCH_JD, GM_SUN_AU3_PER_DAY2, TT_MINUS_UTC_DAYS, ttMinusUtSeconds } from '../../shared/astro/constants';
 import { keplerRates } from '../../shared/astro/kepler';
@@ -465,6 +465,13 @@ describe('derived surfaces', () => {
     renderer.dispose();
   });
 
+  it('builds a body still waiting for its surface without three warning of an undefined map', () => {
+    const warn = vi.spyOn(console, 'warn');
+    twoPlanets().dispose();
+    expect(warn.mock.calls.flat().join(' ')).not.toContain("parameter 'map'");
+    warn.mockRestore();
+  });
+
   it('paints nothing once the system is left', async () => {
     const renderer = twoPlanets();
     renderer.dispose();