Enhance Cospend with debt breakdown and predefined users

- Add EnhancedBalance component with integrated single-user debt display
- Create DebtBreakdown component for multi-user debt overview
- Add predefined users configuration (alexander, anna)
- Implement personal + equal split payment method
- Add profile pictures throughout payment interfaces
- Integrate debt information with profile pictures in balance view
- Auto-hide debt breakdown when single user (shows in balance instead)
- Support both manual and predefined user management modes

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

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

src/routes/api/cospend/payments/[id]/+server.ts

@@ -75,7 +75,8 @@ export const PUT: RequestHandler = async ({ params, request, locals }) => {
           paymentId: id,
           username: split.username,
           amount: split.amount,
-          proportion: split.proportion
+          proportion: split.proportion,
+          personalAmount: split.personalAmount
         });
       });