Implement event registration functionality: Add EventRegistration model to Prisma schema, enabling user event registrations. Enhance EventsPageSection component with registration checks, calendar view, and improved event display. Refactor event rendering logic to separate upcoming and past events, improving user experience.

prisma/schema.prisma

@@ -44,6 +44,7 @@ model User {
   createdAt     DateTime  @default(now())
   updatedAt     DateTime  @updatedAt
   preferences   UserPreferences?
+  eventRegistrations EventRegistration[]
   
   @@index([score])
   @@index([email])
@@ -75,11 +76,25 @@ model Event {
   status      EventStatus
   createdAt   DateTime    @default(now())
   updatedAt   DateTime    @updatedAt
+  registrations EventRegistration[]
   
   @@index([status])
   @@index([date])
 }
 
+model EventRegistration {
+  id        String   @id @default(cuid())
+  userId    String
+  eventId   String
+  user      User     @relation(fields: [userId], references: [id], onDelete: Cascade)
+  event     Event    @relation(fields: [eventId], references: [id], onDelete: Cascade)
+  createdAt DateTime @default(now())
+  
+  @@unique([userId, eventId])
+  @@index([userId])
+  @@index([eventId])
+}
+
 model SitePreferences {
   id                    String   @id @default("global")
   homeBackground        String?