feat: implement parity checks for 20ft container bookings to ensure even numbers

apps/edr-freight-web/backoffice/src/components/contracts/GlCreateBookingForm.tsx

@@ -874,9 +874,14 @@ export default function GlCreateBookingForm() {
   // Only a customs (Path B) instance being COMPLETED by GL can use the shared
   // wagon: it is GL, not the customer, who links the two bookings. Anything else
   // keeps the historical hard block on odd 20ft.
-  const oddConsolidationAvailable = Boolean(
-    completeBookingId && isContainer && contract?.customsClearingEnabled,
-  );
+  //
+  // Switched OFF for now: consolidation is built end to end (toggle, parent
+  // picker, split entry, paired pricing, approval gate) but not in use, so an
+  // odd 20ft total is rejected outright instead of offering the shared wagon.
+  // Drop the `false &&` to bring the whole flow back.
+  const oddConsolidationAvailable =
+    false &&
+    Boolean(completeBookingId && isContainer && contract?.customsClearingEnabled);
 
   // Auto-on: entering an odd 20ft total opens the consolidation panel by itself,
   // once. GL can still switch it off — then odd is blocked exactly as before.
@@ -965,10 +970,11 @@ export default function GlCreateBookingForm() {
       !cargoDescriptionError
     : !bulkErrors.quantity && !bulkErrors.hazardous && !bulkErrors.reefer;
 
-  // The unpaired 20ft container is resolved by the shared wagon, so with an
-  // active consolidation an odd total stops being a blocker; without one it
-  // blocks exactly as before.
-  const oddBlocksSubmit = hasOdd20ft && !consolidationActive;
+  // Consolidation (sharing the wagon with another customer's odd booking) is
+  // built but switched off for now, so an odd 20ft total always blocks — the
+  // shared wagon no longer resolves the unpaired container. Flip this back to
+  // `hasOdd20ft && !consolidationActive` to re-enable the shared-wagon path.
+  const oddBlocksSubmit = hasOdd20ft;
 
   // Partner side: a linked partner must be picked, carry an odd 20ft count of
   // its own (odd + odd = even fills the wagon) and have complete unit details.
@@ -2168,7 +2174,23 @@ export default function GlCreateBookingForm() {
         }}
       >
         <Box maw={896} mx="auto">
-          {showErrors && !formValid ? (
+          {/* The review button is disabled on an odd 20ft total, so the click
+              that would surface the errors never lands — state the reason here
+              rather than leaving it in a tooltip nobody hovers. */}
+          {oddBlocksSubmit ? (
+            <Alert
+              color="red"
+              variant="light"
+              radius="md"
+              icon={<AlertCircle size={16} />}
+              mb="sm"
+              title={`Odd number of 20ft containers (${ft20Total})`}
+            >
+              20ft containers travel two per wagon, so they must be booked in
+              even numbers. Add one more 20ft container or remove one — book{" "}
+              {ft20Total + 1} or {ft20Total - 1} instead of {ft20Total}.
+            </Alert>
+          ) : showErrors && !formValid ? (
             <Alert
               color="red"
               variant="light"