Verbessere die Berechnung der Geschenkekosten in FalukantService und füge Tests für die Funktion hinzu

backend/tools/simulate_getGiftCost.js

@@ -0,0 +1,20 @@
+function getGiftCostLocal(value, titleOfNobility, lowestTitleOfNobility) {
+  const val = Number(value) || 0;
+  const title = Number(titleOfNobility) || 1;
+  const lowest = Number(lowestTitleOfNobility) || 1;
+  const titleLevel = title - lowest + 1;
+  const cost = Math.round(val * Math.pow(1 + titleLevel * 0.3, 1.3) * 100) / 100;
+  return Number.isFinite(cost) ? cost : 0;
+}
+
+const cases = [
+  { giftValue: 100, title: 3, lowest: 1 },
+  { giftValue: '200', title: '2', lowest: '1' },
+  { giftValue: null, title: null, lowest: null },
+  { giftValue: undefined, title: undefined, lowest: undefined },
+  { giftValue: 'abc', title: 5, lowest: 1 }
+];
+
+for (const c of cases) {
+  console.log(`in=${JSON.stringify(c)} -> cost=${getGiftCostLocal(c.giftValue, c.title, c.lowest)}`);
+}