Say that Pluto's tilt is checked against its own IAU pole, not against Horizons

The ETL's obliquity check, its failure message and the renderer spec's test name all compared
Pluto's drawn tilt with "the obliquity Horizons gives", as 1c86584 and cdf474b said too. Horizons'
Pluto page states none (grep -i obliq finds only the page's IAU76 frame note); the 119.6 degrees is
hand-entered in fetchSolarSystem.ts from the IAU WGCCRE 2015 pole (RA 132.993, Dec -6.163), which
with Pluto's orbit gives 119.609. So for Pluto the check confirms that the kernel's pole and the
sense of W were read as written, which it would still catch misread, but not the pole against a
second source.

The build.ts comment says so, its message names Pluto's reference as its IAU pole, and the spec's
test name and comment no longer attribute Pluto's tilt to Horizons. Labels only; no behaviour
changes.

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

tools/etl/build.ts

@@ -209,6 +209,10 @@ const DAY_OFFSET_CEILINGS: Record<string, number> = { neptune: 0.01 };
  * a planet's north pole by the side of the solar system it lies on, whichever way the planet turns.
  * Measured on this catalogue: at most 0.058 degrees (Venus, 177.358 against 177.3). Taken as the
  * pole alone, Venus comes out at 2.6 degrees and Uranus at 82.2, which is what this catches.
+ *
+ * Pluto's Horizons page states no obliquity: its 119.6 is worked out from the IAU pole itself (see
+ * `BodySpec.obliquityDeg`), so for Pluto this checks only that the kernel's pole and W were read as
+ * written, not the pole against a second source.
  */
 const MAX_OBLIQUITY_OFFSET_DEG = 0.1;
 
@@ -327,7 +331,7 @@ function validateBodies(bodies: BodyRecord[], horizonsOrbits: Map<string, Orbita
         const obliquity = angleBetweenDeg(axis, body.laplacePole ? laplacePlaneToEquatorial(normal, body.laplacePole) : eclipticToEquatorial(normal));
         assertCondition(
           Math.abs(obliquity - body.obliquityDeg) <= MAX_OBLIQUITY_OFFSET_DEG,
-          `${body.name}'s IAU spin axis is ${obliquity.toFixed(3)} degrees from its orbit's pole, where Horizons gives an obliquity of ${body.obliquityDeg} (at most ${MAX_OBLIQUITY_OFFSET_DEG} apart expected) — the pole or the sense of W was read wrongly.`
+          `${body.name}'s IAU spin axis is ${obliquity.toFixed(3)} degrees from its orbit's pole, where ${body.id === 'pluto' ? 'its IAU pole' : 'Horizons'} gives an obliquity of ${body.obliquityDeg} (at most ${MAX_OBLIQUITY_OFFSET_DEG} apart expected) — the pole or the sense of W was read wrongly.`
         );
         spins.push(`${body.id} tilt ${obliquity.toFixed(3)}`);
       }