Remove dynamic form builder and complete RoundProject→roundId migration

Major cleanup and schema migration:
- Remove unused dynamic form builder system (ApplicationForm, ApplicationFormField, etc.)
- Complete migration from RoundProject junction table to direct Project.roundId
- Add sortOrder and entryNotificationType fields to Round model
- Add country field to User model for mentor matching
- Enhance onboarding with profile photo and country selection steps
- Fix all TypeScript errors related to roundProjects references
- Remove unused libraries (@radix-ui/react-toast, embla-carousel-react, vaul)

Files removed:
- admin/forms/* pages and related components
- admin/onboarding/* pages
- applicationForm.ts and onboarding.ts routers
- Dynamic form builder Prisma models and enums

Schema changes:
- Removed ApplicationForm, ApplicationFormField, OnboardingStep, ApplicationFormSubmission, SubmissionFile models
- Removed FormFieldType and SpecialFieldType enums
- Added Round.sortOrder, Round.entryNotificationType
- Added User.country

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

src/components/layouts/admin-sidebar.tsx

@@ -28,7 +28,6 @@ import {
   ChevronRight,
   BookOpen,
   Handshake,
-  FileText,
   CircleDot,
   History,
   Trophy,
@@ -91,11 +90,6 @@ const navigation = [
     href: '/admin/partners' as const,
     icon: Handshake,
   },
-  {
-    name: 'Onboarding',
-    href: '/admin/onboarding' as const,
-    icon: FileText,
-  },
 ]
 
 // Admin-only navigation