Enhance duplicate detection with sales/admin access and field updates

- Extend duplicate detection access from admin-only to sales/admin users
- Update field names for better clarity (Email → Email Address, etc.)
- Add duplicate notification banner to expenses page
- Improve authorization checks with role-based access control

pages/dashboard/expenses.vue

@@ -1,5 +1,8 @@
 <template>
   <div class="pa-4">
+    <!-- Duplicate notification banner for sales/admin -->
+    <ExpenseDuplicateNotificationBanner />
+    
     <!-- Header Section -->
     <div class="d-flex align-center mb-6">
       <div>