Add reject step functionality to contract approval process

- Implemented rejection handling in ContractApprovalStepsCard with a modal for rejection reasons.
- Updated useContractMutations to include rejectStep mutation.
- Added REJECT_STEP URL constant for API integration.
- Enhanced ContractClearanceDetailPage to utilize linkedBookingId for improved booking handling.

apps/edr-freight-web/backoffice/src/hooks/contracts/useContracts.ts

@@ -181,6 +181,15 @@ export function useContractMutations(contractId: string) {
     onError: () => toast.error("Failed to approve step"),
   });
 
+  // Per-step rejection by an approver (line staff / director / CEO). Terminal:
+  // the contract goes to REJECTED and the customer must create a new one.
+  const rejectStep = useMutation({
+    mutationFn: ({ stepId, reason }: { stepId: string; reason: string }) =>
+      contractsService.rejectStep({ id: contractId, stepId, reason }),
+    onSuccess: (data) => onSuccess(data, "Contract rejected"),
+    onError: () => toast.error("Failed to reject step"),
+  });
+
   // Manual fallback generate — used only if auto-generation failed.
   const generateContract = useMutation({
     mutationFn: () => contractsService.generateContract(contractId),
@@ -210,6 +219,7 @@ export function useContractMutations(contractId: string) {
     requestChanges.isPending ||
     reject.isPending ||
     approveStep.isPending ||
+    rejectStep.isPending ||
     generateContract.isPending ||
     signContract.isPending ||
     createBooking.isPending;
@@ -219,6 +229,7 @@ export function useContractMutations(contractId: string) {
     requestChanges,
     reject,
     approveStep,
+    rejectStep,
     generateContract,
     signContract,
     createBooking,