feat(auth): add user invitation flow with account setup

- add `createAccountSetup`, `verifyAccountSetupToken`, `deleteAccountSetupToken` to verifications core
- add `completeAccountSetup` function to auth core for password creation on invite
- add `InvitationEmail` template for sending invite links
- add `SetupAccountPage` client page for invited users to set their password
- add `UserCreateModal` admin component to invite new users
- wire invitation action and API endpoint in auth feature
- update admin `UsersPage` to include user creation modal
- update auth and admin README docs

src/features/admin/pages/UsersPage.client.js

@@ -7,8 +7,9 @@ import { PencilEdit01Icon } from '@zen/core/shared/icons';
 import { useToast } from '@zen/core/toast';
 import AdminHeader from '../components/AdminHeader.js';
 import UserEditModal from '../components/UserEditModal.client.js';
+import UserCreateModal from '../components/UserCreateModal.client.js';
 
-const UsersPageClient = ({ currentUserId }) => {
+const UsersPageClient = ({ currentUserId, refreshKey }) => {
     const toast = useToast();
     const [users, setUsers] = useState([]);
     const [loading, setLoading] = useState(true);
@@ -126,7 +127,7 @@ const UsersPageClient = ({ currentUserId }) => {
 
     useEffect(() => {
         fetchUsers();
-    }, [sortBy, sortOrder, pagination.page, pagination.limit]);
+    }, [sortBy, sortOrder, pagination.page, pagination.limit, refreshKey]);
 
     const handlePageChange = (newPage) => setPagination(prev => ({ ...prev, page: newPage }));
     const handleLimitChange = (newLimit) => setPagination(prev => ({ ...prev, limit: newLimit, page: 1 }));
@@ -168,12 +169,30 @@ const UsersPageClient = ({ currentUserId }) => {
     );
 };
 
-const UsersPage = ({ user }) => (
-    <div className="flex flex-col gap-4 sm:gap-6 lg:gap-8">
-        <AdminHeader title="Utilisateurs" description="Gérez les comptes utilisateurs" />
-        <UsersPageClient currentUserId={user?.id} />
-    </div>
-);
+const UsersPage = ({ user }) => {
+    const [createModalOpen, setCreateModalOpen] = useState(false);
+    const [refreshKey, setRefreshKey] = useState(0);
+
+    return (
+        <div className="flex flex-col gap-4 sm:gap-6 lg:gap-8">
+            <AdminHeader
+                title="Utilisateurs"
+                description="Gérez les comptes utilisateurs"
+                action={
+                    <Button variant="primary" onClick={() => setCreateModalOpen(true)}>
+                        Nouvel utilisateur
+                    </Button>
+                }
+            />
+            <UsersPageClient currentUserId={user?.id} refreshKey={refreshKey} />
+            <UserCreateModal
+                isOpen={createModalOpen}
+                onClose={() => setCreateModalOpen(false)}
+                onSaved={() => setRefreshKey(k => k + 1)}
+            />
+        </div>
+    );
+};
 
 export default UsersPage;