feat: remove Account page and add PassthroughLanding page

- Deleted the Account page and its associated logic.
- Introduced a new PassthroughLanding page for users without management access.
- Updated Settings page to conditionally display the Users link for admin users.
- Enhanced UsersPage to support passthrough user role, including invite functionality and user detail modal.
- Updated tests to reflect changes in user roles and navigation.

frontend/src/context/AuthContextValue.ts

@@ -2,7 +2,7 @@ import { createContext } from 'react';
 
 export interface User {
   user_id: number;
-  role: string;
+  role: 'admin' | 'user' | 'passthrough';
   name?: string;
   email?: string;
 }