feat: fuel surcharge per lane and cargo type

apps/edr-freight-api/src/contracts/contract-rate-schedule.builder.ts

@@ -193,17 +193,26 @@ export class ContractRateScheduleBuilder {
     return rate.tradeDirection === want;
   }
 
-  /** Fuel row — the lane matters, so it rides along in the charge label. */
+  /**
+   * Fuel row — the lane matters, so it rides along in the charge label.
+   * Per-liter collapses to one flat total (base liters × rate value); the
+   * customer only ever sees the final price.
+   */
   private fuelRow(rate: Rate): RateScheduleRow {
     const origin = rate.originYard?.label ?? rate.originYard?.code ?? '—';
     const destination =
       rate.destinationYard?.label ?? rate.destinationYard?.code ?? '—';
+    const perLiter = rate.rateUnit === 'PER_LITER';
     return {
       route: `Fuel surcharge (${origin} → ${destination})`,
       cargo: this.cargoLabel(rate),
       currency: rate.currency,
-      amount: this.formatAmount(rate.rateValue),
-      unit: this.unitLabel(rate.rateUnit),
+      amount: this.formatAmount(
+        perLiter
+          ? Number(rate.baseLiters ?? 0) * Number(rate.rateValue)
+          : rate.rateValue,
+      ),
+      unit: perLiter ? 'flat' : this.unitLabel(rate.rateUnit),
     };
   }