fix(hr): prevent crash when baseSalary is undefined

frontend/src/app/hr/page.tsx

@@ -710,7 +710,7 @@ function HRContent() {
                         </td>
                         <td className="px-6 py-4">
                           <span className="text-sm font-semibold text-gray-900">
-                            {employee.baseSalary.toLocaleString()} SAR
+                            {Number(employee.baseSalary ?? 0).toLocaleString()} SAR
                           </span>
                         </td>
                         <td className="px-6 py-4">
@@ -881,4 +881,4 @@ export default function HRPage() {
       <HRContent />
     </ProtectedRoute>
   )
-}
+}