feat: implement public booking cancellation feature

- Added cancelPublicBooking handler to manage booking cancellations.
- Updated public booking service to include cancellation logic.
- Created cancelPublicBooking schema for input validation.
- Modified public booking confirmation page to allow users to cancel their bookings.
- Enhanced email service to send cancellation confirmation emails.
- Made customerEmail field required in booking schemas and updated related components.
- Updated API client to support cancellation requests.
- Added migration to enforce non-nullable customer_email fields in the database.

apps/backend/prisma/court.prisma

@@ -85,7 +85,7 @@ model CourtBooking {
   endTime       String              @map("end_time") @db.VarChar(5)
   customerName  String              @map("customer_name") @db.VarChar(120)
   customerPhone String              @map("customer_phone") @db.VarChar(30)
-  customerEmail String?             @map("customer_email") @db.VarChar(254)
+  customerEmail String              @map("customer_email") @db.VarChar(254)
   status        CourtBookingStatus  @default(CONFIRMED)
   createdAt     DateTime            @default(now()) @map("created_at")
   updatedAt     DateTime            @updatedAt @map("updated_at")
@@ -108,7 +108,7 @@ model CourtBookingLog {
   newStatus      CourtBookingStatus  @map("new_status")
   customerName  String               @map("customer_name") @db.VarChar(120)
   customerPhone String               @map("customer_phone") @db.VarChar(30)
-  customerEmail String?              @map("customer_email") @db.VarChar(254)
+  customerEmail String               @map("customer_email") @db.VarChar(254)
   changedAt      DateTime            @default(now()) @map("changed_at")
 
   @@map("court_booking_logs")

apps/backend/prisma/migrations/20260605121954_make_email_required/migration.sql

@@ -0,0 +1,16 @@
+/*
+  Warnings:
+
+  - Made the column `customer_email` on table `court_booking_logs` required. This step will fail if there are existing NULL values in that column.
+  - Made the column `customer_email` on table `court_bookings` required. This step will fail if there are existing NULL values in that column.
+
+*/
+-- Backfill existing NULL values with placeholder
+UPDATE "court_booking_logs" SET "customer_email" = 'missing@playzer.app' WHERE "customer_email" IS NULL;
+UPDATE "court_bookings" SET "customer_email" = 'missing@playzer.app' WHERE "customer_email" IS NULL;
+
+-- AlterTable
+ALTER TABLE "court_booking_logs" ALTER COLUMN "customer_email" SET NOT NULL;
+
+-- AlterTable
+ALTER TABLE "court_bookings" ALTER COLUMN "customer_email" SET NOT NULL;