fix(targets): classify a weight with the height its band was built from

The child-band change left the classification dividing by the record's
height where it had checked the adult-band height, which the type checker
refused. Both now read the same value.

src/lib/targets/vitals-builder.ts

@@ -194,7 +194,7 @@ export function buildVitalTargets({
     weightTargetOverride ?? (whoHeightCm ? getWeightRange(whoHeightCm) : null);
   let weightClassification: TargetItem["classification"] = null;
   if (latestByType.WEIGHT != null && whoHeightCm) {
-    const heightM = heightCm / 100;
+    const heightM = whoHeightCm / 100;
     const classification = classifyBMI(
       latestByType.WEIGHT / (heightM * heightM),
     );