add payment and integration with midtrans

prisma/migrations/20260508160000_booking_unique_trip_user/migration.sql

@@ -0,0 +1,5 @@
+-- DropIndex (replace solo userId index dengan unique compound yang lebih berguna)
+DROP INDEX "Booking_userId_idx";
+
+-- CreateIndex (unique compound, juga jadi index untuk lookup by tripId+userId)
+CREATE UNIQUE INDEX "Booking_tripId_userId_key" ON "Booking"("tripId", "userId");

prisma/schema.prisma

@@ -262,8 +262,11 @@ model Booking {
   createdAt DateTime @default(now())
   updatedAt DateTime @updatedAt
 
+  /// Konsistensi: 1-1 ke participant via participantId, dan participant unique
+  /// per (tripId, userId). Constraint ini eksplisit + jadi index untuk query
+  /// `findByTripAndUser`.
+  @@unique([tripId, userId])
   @@index([tripId, status])
-  @@index([userId])
 }
 
 enum BookingStatus {