Implement contract document download functionality and enhance clearance review status checks

- Added methods to assert clearance reviewable, finalizable, and uploadable statuses in the ContractClearanceService.
- Introduced a new endpoint in ContractsController for downloading contract PDFs.
- Implemented download functionality in the contracts service for both backoffice and portal applications.
- Updated UI components to include download buttons for contract PDFs in relevant pages.
- Enhanced contract request and view pages to support contract document downloads.

apps/edr-freight-web/backoffice/src/components/layout/route-meta.ts

@@ -184,6 +184,13 @@ const ROUTE_META: Array<{ prefix: string; meta: PageMeta }> = [
       subtitle: "Manage dropdown options used across the platform",
     },
   },
+  {
+    prefix: "/dashboard/configuration/contract-validity-periods",
+    meta: {
+      title: "Contract validity periods",
+      subtitle: "Validity options staff choose when accepting a submitted contract",
+    },
+  },
   {
     prefix: "/dashboard/configuration/train-scheduling-rules",
     meta: {