Remove all obsolete authentication, settings, admin, and demo-related components and pages

- Eliminated redundant components, pages, and layouts related to authentication (`login`, `register`, `password-reset`, etc.), user settings, admin, and demos.
- Simplified the frontend structure by removing unused dynamic imports, forms, and test code.
- Refactored configurations and metadata imports to exclude references to removed features.
- Streamlined the project for future development and improved maintainability by discarding legacy and unused code.

frontend/src/components/auth/AuthGuard.tsx

@@ -7,7 +7,7 @@
 'use client';
 
 import { useEffect, useState } from 'react';
-import { useRouter, usePathname } from 'next/navigation';
+import { useRouter, usePathname } from '@/lib/i18n/routing';
 import { useAuth } from '@/lib/auth/AuthContext';
 import { useMe } from '@/lib/api/hooks/useAuth';
 import { AuthLoadingSkeleton } from '@/components/layout';

frontend/src/components/auth/LoginForm.tsx

@@ -7,7 +7,7 @@
 'use client';
 
 import { useState } from 'react';
-import Link from 'next/link';
+import { Link } from '@/lib/i18n/routing';
 import { useForm } from 'react-hook-form';
 import { zodResolver } from '@hookform/resolvers/zod';
 import { z } from 'zod';

frontend/src/components/auth/PasswordResetConfirmForm.tsx

@@ -7,7 +7,7 @@
 'use client';
 
 import { useState } from 'react';
-import Link from 'next/link';
+import { Link } from '@/lib/i18n/routing';
 import { useForm } from 'react-hook-form';
 import { zodResolver } from '@hookform/resolvers/zod';
 import { z } from 'zod';

frontend/src/components/auth/PasswordResetRequestForm.tsx

@@ -7,7 +7,7 @@
 'use client';
 
 import { useState } from 'react';
-import Link from 'next/link';
+import { Link } from '@/lib/i18n/routing';
 import { useForm } from 'react-hook-form';
 import { zodResolver } from '@hookform/resolvers/zod';
 import { z } from 'zod';

frontend/src/components/auth/RegisterForm.tsx

@@ -7,7 +7,7 @@
 'use client';
 
 import { useState } from 'react';
-import Link from 'next/link';
+import { Link } from '@/lib/i18n/routing';
 import { useForm } from 'react-hook-form';
 import { zodResolver } from '@hookform/resolvers/zod';
 import { z } from 'zod';