GEN-4 REW erweitert: alle 3 C-Kombi + pp = REW (Julian bestätigt)

- cReduced(c) = cchm || ch; REW wenn cReduced(c0) && cReduced(c1) && pp
  (cchm/cchm, cchm/ch, ch/ch alle REW; mind. ein volles C = NICHT REW)
- Counterproof-Test: C/cchm + pp und C/ch + pp = nicht REW
- Frozen-Round-Trip-Test: PEW (ch/ch+pp) explizit ausgenommen (intentional
  shadow durch REW-Check per Julian-Regel; PEW bleibt Dropdown-Name)
Gate: build ✓  eslint ✓  vitest 95/95 ✓  e2e 148/148 ✓

gerbil-manager-web/src/genetics/catalog.ts

@@ -253,13 +253,16 @@ export function farbschlagFor(g: Genotype): FarbschlagMatch {
   if (locusToken(g, 'Sp') === 'Sp') modifiers.push('Schecke')
   if (locusToken(g, 'Re') === 'Re') modifiers.push('Rex')
 
-  // GEN-4 REW check: homozygous colourpoint (cchm/cchm) + pink-eyed (pp) = REW.
-  // This combination removes both fur pigment (C locus) and eye pigment (P locus)
-  // regardless of A/D/E/G.  Examples: CP-Gold, CP-Goldfuchs, CP-Elfenbein, CP-Apricot.
-  // Flagged to god for confirmation (condition: cchm×cchm + p×p).
+  // GEN-4 REW check (Julian confirmed + extended): both C alleles reduced (no full 'C')
+  // AND pink-eyed (pp) = REW (Rotaugenweiß), A/D/E/G-independent.
+  //   cchm/cchm + pp → REW  (CP varieties with pink-eye)
+  //   cchm/ch  + pp → REW  (het colourpoint + pink-eye)
+  //   ch/ch    + pp → REW  (this also subsumes the frozen 'Pink Eyed White (PEW)' entry)
+  // Counterproof: at least one full 'C' + pp → NOT REW (residual pigment remains).
   const [c0, c1] = resolvedPair(g, 'C')
   const [p0, p1] = resolvedPair(g, 'P')
-  if (c0 === 'cchm' && c1 === 'cchm' && p0 === 'p' && p1 === 'p') {
+  const cReduced = (c: string) => c === 'cchm' || c === 'ch'
+  if (cReduced(c0) && cReduced(c1) && p0 === 'p' && p1 === 'p') {
     const name = ['REW', ...modifiers].join(' ')
     return { name, base: null, unknown: false }
   }