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

shared-types/src/lib/auth.types.ts

@@ -5,17 +5,21 @@
  */
 
 interface User {
-  id:        string;
-  email:     string;
-  username:  string;
-  avatar?:   string;
-  discordId: string;
-  isAdmin:   boolean;
-  isBanned:  boolean;
-  inDiscord: boolean;
-  isVip:     boolean;
-  isMod:     boolean;
-  isStaff:   boolean;
+  id:            string;
+  email:         string;
+  username:      string;
+  avatar?:       string;
+  slug?:         string;
+  displayName?:  string;
+  bio?:          string;
+  profilePublic: boolean;
+  discordId:     string;
+  isAdmin:       boolean;
+  isBanned:      boolean;
+  inDiscord:     boolean;
+  isVip:         boolean;
+  isMod:         boolean;
+  isStaff:       boolean;
 }
 
 interface JwtPayload {