feat: add social links with validation and Font Awesome icons

Added comprehensive social links functionality to user profiles:

**New Social Platforms:**
- Website (full URL validation)
- GitHub (username format)
- Bluesky (handle format)
- LinkedIn (username format)
- Twitch (username format)
- YouTube (handle or channel ID format)
- Discord Server (invite code format)

**Features:**
- Database schema updated with 7 new optional social link fields
- Backend services and API routes updated to handle all social links
- Settings form with input fields and helpful validation hints
- Profile display with Font Awesome icons for each platform
- Regex validation patterns for all fields with visual feedback
- Green border for valid input, red border for invalid input
- All form inputs use consistent type="text" for uniform styling
- Discord accepts just invite code (constructs full URL automatically)

**Technical Changes:**
- Installed @fortawesome/angular-fontawesome with pinned versions
- Replaced emoji icons with proper Font Awesome components
- Added FontAwesomeModule to profile component
- Updated all User type interfaces across frontend and backend
- Updated UserService mappings in all methods
- Added comprehensive regex patterns matching platform requirements

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

api/prisma/schema.prisma

@@ -186,6 +186,13 @@ model User {
   displayName   String?
   bio           String?
   profilePublic Boolean        @default(true)
+  website       String?
+  discordServer String?
+  bluesky       String?
+  github        String?
+  linkedin      String?
+  twitch        String?
+  youtube       String?
   isAdmin       Boolean        @default(false)
   isBanned      Boolean        @default(false)
   inDiscord     Boolean        @default(false)