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/api/__tests__/user.test.ts

@@ -1,6 +1,6 @@
 import { beforeEach, describe, expect, it, vi } from 'vitest'
 import client from '../client'
-import { getProfile, regenerateApiKey, updateProfile } from '../user'
+import { getProfile, regenerateApiKey, updateProfile } from '../users'
 
 vi.mock('../client', () => ({
   default: {