fix(operations): last-mile assign until load fully trucked + 40ft cap

Assign was gated on any truck assigned, blocking multi-truck
deliveries. Gate on remaining containers (or bulk tonnage) instead, show
covered/total in the modal, cap a 40ft container to one truck with no
size mixing (mirrors assertTruckLoad), and lock arrived/departed rows.

apps/edr-freight-web/backoffice/src/components/warehouses/FeePreviewModal.tsx

@@ -37,6 +37,14 @@ function fmtDate(iso: string | null) {
   return new Date(iso).toLocaleDateString();
 }
 
+const UNIT_LABEL_PLURAL: Record<string, string> = {
+  container: 'Containers',
+  truck: 'Trucks',
+  ton: 'Tons',
+  item: 'Items',
+};
+const unitLabelPlural = (unitLabel?: string) => UNIT_LABEL_PLURAL[unitLabel ?? 'container'] ?? 'Containers';
+
 const money = (amount: number, currency: string) =>
   `${Number(amount).toLocaleString()} ${currency === 'ETB' ? 'Birr (ETB)' : currency}`;
 
@@ -72,8 +80,11 @@ function FeeCard({ fee }: { fee: FeePreview }) {
           <Row label="Period" value={`${fmtDate(fee.startDate)} → ${fmtDate(fee.endDate)}${fee.endIsOpen ? ' (today)' : ''}`} />
           <Row label="Elapsed days" value={String(fee.elapsedDays)} />
           <Row label="Chargeable days" value={`${fee.chargeableDays} (after ${fee.freeDays} free)`} />
-          <Row label="Containers" value={String(fee.containerCount ?? 1)} />
-          <Row label="Billable units" value={`${fee.billableUnits ?? fee.chargeableDays} container-day(s)`} />
+          <Row label={unitLabelPlural(fee.unitLabel)} value={String(fee.containerCount ?? 1)} />
+          <Row
+            label="Billable units"
+            value={`${fee.billableUnits ?? fee.chargeableDays} ${fee.unitLabel ?? 'container'}-day(s)`}
+          />
           {(fee.tiers ?? []).map((tier) => (
             <Row
               key={`${tier.appliedFromDay}-${tier.appliedToDay}-${tier.ratePerDay}`}