Add complete settlement system with visual distinction

- Add settlement category with handshake emoji (🤝)
- Create settlement page for recording debt payments with user → user flow
- Implement settlement detection and visual styling across all views
- Add conditional "Settle Debts" button (hidden when balance is 0)
- Style settlement payments distinctly in recent activity with large profile pictures
- Add settlement flow styling in payments overview with green theme
- Update backend validation and Mongoose schema for settlement category
- Fix settlement receiver detection with proper user flow logic

🤝 Generated with [Claude Code](https://claude.ai/code)

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

src/lib/components/EnhancedBalance.svelte

@@ -43,16 +43,6 @@
     // Recalculate when debtData changes
     singleDebtUser = getSingleDebtUser();
     shouldShowIntegratedView = singleDebtUser !== null;
-    
-    // Temporary debug logging
-    if (!loading) {
-      console.log('🔍 Debug Info:');
-      console.log('- debtData:', debtData);
-      console.log('- whoOwesMe length:', debtData.whoOwesMe.length);
-      console.log('- whoIOwe length:', debtData.whoIOwe.length);
-      console.log('- singleDebtUser:', singleDebtUser);
-      console.log('- shouldShowIntegratedView:', shouldShowIntegratedView);
-    }
   }