notification implemented

packages/database/prisma/schema.prisma

@@ -377,6 +377,7 @@ enum AdminAction {
 }
 
 enum NotificationType {
+  ACCOUNT_CREATED
   NEW_BOOKING
   BOOKING_CANCELLED
   PAYMENT_RECEIVED
@@ -540,6 +541,7 @@ model BillingAccount {
   isPrimary              Boolean                    @default(true)
   legalName              String
   billingEmail           String
+  preferredLanguage      String                     @default("en")
   billingAddress         Json?
   taxId                  String?
   taxExempt              Boolean                    @default(false)
@@ -1218,6 +1220,8 @@ model Notification {
   body              String
   data              Json?
   channel           NotificationChannel
+  templateKey       String?
+  locale            String              @default("en")
   status            NotificationStatus  @default(PENDING)
   sentAt            DateTime?
   failReason        String?
@@ -1231,6 +1235,26 @@ model Notification {
   @@map("notifications")
 }
 
+model NotificationTemplate {
+  id                String              @id @default(cuid())
+  templateKey       String
+  category          String
+  channel           NotificationChannel
+  locale            String
+  subject           String?
+  body              String
+  requiredVariables Json?
+  optionalVariables Json?
+  version           Int                 @default(1)
+  isActive          Boolean             @default(true)
+  createdAt         DateTime            @default(now())
+  updatedAt         DateTime            @updatedAt
+
+  @@unique([templateKey, channel, locale, version])
+  @@index([templateKey, channel, locale, isActive])
+  @@map("notification_templates")
+}
+
 model NotificationPreference {
   id               String              @id @default(cuid())
   employeeId       String?