feat: implement user profiles and settings

Add comprehensive user profile system allowing users to showcase
their activity and customize their profiles.

Database Changes:
- Added profile fields to User model: slug, displayName, bio, profilePublic
- Added index on slug field for efficient lookups

API Changes:
- Added GET /users/me endpoint to fetch current user
- Added PUT /users/me endpoint to update user settings
- Added GET /users/profile/:identifier endpoint for public profiles
- Updated UserService with profile methods and statistics
- Modified AuthService to include profile fields in user responses

Frontend Changes:
- Created ProfileComponent to display user profiles with stats
- Created SettingsComponent for profile customization
- Added profile and settings routes
- Updated header dropdown menu with profile links
- Enhanced UserService with profile methods
- Added updateUser method to AuthService

Features:
- Custom profile slugs for clean URLs
- Display names separate from usernames
- User bios (up to 500 characters)
- Public/private profile toggle
- Activity statistics (suggestions, likes, comments, acceptance rate)
- Badge display (Staff, Mod, VIP, Discord Member)
- Beautiful witch-themed styling

Closes #45

apps/frontend/src/app/app.routes.ts

@@ -49,6 +49,14 @@ export const appRoutes: Route[] = [
     path: 'my-likes',
     loadComponent: () => import('./components/my-likes/my-likes.component').then(m => m.MyLikesComponent)
   },
+  {
+    path: 'profile/:identifier',
+    loadComponent: () => import('./components/profile/profile.component').then(m => m.ProfileComponent)
+  },
+  {
+    path: 'settings',
+    loadComponent: () => import('./components/settings/settings.component').then(m => m.SettingsComponent)
+  },
   {
     path: '**',
     redirectTo: ''