fix(contacts): align contact export permissions (#14601)

Allows contact managers to export and import contacts from the Contacts
page while keeping plain agents blocked. The contacts action menu now
mirrors backend permissions for both export and import.

## Closes

- https://linear.app/chatwoot/issue/CW-4438/contact-export-is-broken

## What changed

- Allows Enterprise custom roles with `contact_manage` to pass
`ContactPolicy#export?` and `ContactPolicy#import?`.
- Shows Export and Import to admins and contact managers only.
- Adds Enterprise policy coverage for contact export and import.

## Screenshots

Admin: Export and Import are available.

<img width="3840" height="2160" alt="Admin contact actions with Export
and Import visible"
src="https://github.com/user-attachments/assets/2b2cdaf2-ca8f-470d-be34-31cba68b9dce"
/>

Contact manager: Export and Import are available.

<img width="3840" height="2160" alt="Contact manager contact actions
with Export and Import visible"
src="https://github.com/user-attachments/assets/48fc038b-2e78-4d0c-ba17-a5965641bd88"
/>

Regular agent: Export and Import are hidden.

<img width="3840" height="2160" alt="Regular agent contact actions with
Export and Import hidden"
src="https://github.com/user-attachments/assets/a63b5731-743a-4223-8dab-ce58383067fe"
/>

## How to test

- Sign in as an administrator and open Contacts; the action menu shows
Export and Import.
- Sign in as a custom-role user with `contact_manage`; the action menu
shows Export and Import.
- Sign in as a plain agent; Export and Import are not available and both
APIs remain unauthorized.

app/javascript/dashboard/components-next/Contacts/ContactsHeader/components/ContactMoreActions.vue

@@ -1,34 +1,48 @@
 <script setup>
-import { ref } from 'vue';
+import { computed, ref } from 'vue';
 import { useI18n } from 'vue-i18n';
 
 import Button from 'dashboard/components-next/button/Button.vue';
 import DropdownMenu from 'dashboard/components-next/dropdown-menu/DropdownMenu.vue';
+import { usePolicy } from 'dashboard/composables/usePolicy';
 
 const emit = defineEmits(['add', 'import', 'export']);
 
 const { t } = useI18n();
+const { checkPermissions } = usePolicy();
 
-const contactMenuItems = [
+const contactMenuItems = computed(() => [
   {
     label: t('CONTACTS_LAYOUT.HEADER.ACTIONS.CONTACT_CREATION.ADD_CONTACT'),
     action: 'add',
     value: 'add',
     icon: 'i-lucide-plus',
   },
-  {
-    label: t('CONTACTS_LAYOUT.HEADER.ACTIONS.CONTACT_CREATION.EXPORT_CONTACT'),
-    action: 'export',
-    value: 'export',
-    icon: 'i-lucide-upload',
-  },
-  {
-    label: t('CONTACTS_LAYOUT.HEADER.ACTIONS.CONTACT_CREATION.IMPORT_CONTACT'),
-    action: 'import',
-    value: 'import',
-    icon: 'i-lucide-download',
-  },
-];
+  ...(checkPermissions(['administrator', 'contact_manage'])
+    ? [
+        {
+          label: t(
+            'CONTACTS_LAYOUT.HEADER.ACTIONS.CONTACT_CREATION.EXPORT_CONTACT'
+          ),
+          action: 'export',
+          value: 'export',
+          icon: 'i-lucide-upload',
+        },
+      ]
+    : []),
+  ...(checkPermissions(['administrator', 'contact_manage'])
+    ? [
+        {
+          label: t(
+            'CONTACTS_LAYOUT.HEADER.ACTIONS.CONTACT_CREATION.IMPORT_CONTACT'
+          ),
+          action: 'import',
+          value: 'import',
+          icon: 'i-lucide-download',
+        },
+      ]
+    : []),
+]);
 const showActionsDropdown = ref(false);
 
 const handleContactAction = ({ action }) => {