Test that a Gaia star with no measured band is still labelled Gaia's

describingCatalogue calls a star Gaia's when its source is gaia and its band is not V. 44 Gaia
sources in the shipped catalogue have no G (Gaia DR3 40091256260676736 among them), and nothing
tested them: narrowing the rule to band G, which would relabel all 44 "HYG" and count them as HYG
in the neighbourhood census, passed the suite. The existing test already builds such a star and
now checks its Source row as well.

Control: the rule narrowed to band G fails "says a stand-in magnitude was not measured, and leaves
out a colour there is none of" (1 of 797).

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

src/app/features/galaxy-system/star-readouts.spec.ts

@@ -54,6 +54,8 @@ describe('starReadouts', () => {
     const unmeasured = starReadouts({ ...GAIA_STAR, magnitude: 12, magnitudeBand: undefined, colorIndex: null, colorSystem: undefined });
     expect(value(unmeasured, 'Magnitude')).toBe('Not measured');
     expect(value(unmeasured, 'Colour')).toBeUndefined();
+    // Still Gaia's star, as the 44 Gaia sources with no G are: no band is not HYG's V.
+    expect(value(unmeasured, 'Source')).toBe('Gaia DR3');
   });
 
   it('gives the distance with its uncertainty', () => {