feat: implement 20ft container weight-pairing validation

- Added ContainerValidationService to handle 20ft weight-pairing logic.
- Introduced validate20ftWeightPairing utility function to check weight differences.
- Updated BookingPricingService to include overweight line details and pairing errors in price response.
- Enhanced BookingTransitionService to reject submissions with unpairable 20ft containers.
- Created ShipmentValidation interface for pre-submit validation of container contracts.
- Integrated shipment validation into the contract booking process, providing warnings for overweight containers and hard blocks for pairing errors.
- Updated front-end components to display validation results and prevent submission when errors are present.

apps/edr-freight-web/backoffice/src/lib/permissions.ts

@@ -73,6 +73,38 @@ export function getPermissionKeys(user: AuthUser | null | undefined): string[] {
   return [...keys];
 }
 
+/** Position keys held by the user (e.g. "ethiopian_gl", "djibouti_gl"). */
+export function getPositionKeys(user: AuthUser | null | undefined): string[] {
+  if (!user) return [];
+  const keys = new Set<string>();
+  for (const emp of user.employee ?? []) {
+    for (const pos of emp.positions ?? []) {
+      if (pos.key) keys.add(pos.key);
+    }
+  }
+  return [...keys];
+}
+
+export function hasPosition(
+  user: AuthUser | null | undefined,
+  positionKey: string,
+): boolean {
+  return getPositionKeys(user).includes(positionKey);
+}
+
+export const POSITION_KEYS = {
+  ethiopianGl: "ethiopian_gl",
+  djiboutiGl: "djibouti_gl",
+} as const;
+
+export function isEthiopianGl(user: AuthUser | null | undefined): boolean {
+  return hasPosition(user, POSITION_KEYS.ethiopianGl);
+}
+
+export function isDjiboutiGl(user: AuthUser | null | undefined): boolean {
+  return hasPosition(user, POSITION_KEYS.djiboutiGl);
+}
+
 export function isSuperAdmin(user: AuthUser | null | undefined): boolean {
   if (user?.isSuperAdmin) return true;
   return Boolean(user?.roles?.some((r) => r.key === "super_admin"));