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>

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

@@ -13,6 +13,13 @@ interface User {
   displayName?:  string;
   bio?:          string;
   profilePublic: boolean;
+  website?:      string;
+  discordServer?: string;
+  bluesky?:      string;
+  github?:       string;
+  linkedin?:     string;
+  twitch?:       string;
+  youtube?:      string;
   discordId:     string;
   isAdmin:       boolean;
   isBanned:      boolean;