chore: migrate to PostgreSQL with Prisma

prisma/schema.prisma

@@ -0,0 +1,43 @@
+// This is your Prisma schema file,
+// learn more about it in the docs: https://pris.ly/d/prisma-schema
+
+generator client {
+  provider = "prisma-client-js"
+}
+
+datasource db {
+  provider = "postgresql"
+  url      = env("DATABASE_URL")
+}
+
+model User {
+  id               String               @id @default(cuid())
+  email            String               @unique
+  name             String?
+  password         String
+  role             String               @default("DOMAIN_ADMIN") // SUPER_ADMIN or DOMAIN_ADMIN
+  domains          String[]             @default([])           // ["*"] or list of domains
+  telegramId       String?
+  mailboxMappings  MailboxMapping[]
+  notificationConfigs NotificationConfig[]
+  createdAt        DateTime             @default(now())
+  updatedAt        DateTime             @updatedAt
+}
+
+model MailboxMapping {
+  id        String   @id @default(cuid())
+  email     String   @unique
+  userId    String
+  user      User     @relation(fields: [userId], references: [id], onDelete: Cascade)
+  createdAt DateTime @default(now())
+}
+
+model NotificationConfig {
+  id        String   @id @default(cuid())
+  userId    String
+  user      User     @relation(fields: [userId], references: [id], onDelete: Cascade)
+  type      String   // e.g., "TELEGRAM", "WEBHOOK"
+  value     String   // e.g., chat_id or webhook url
+  active    Boolean  @default(true)
+  createdAt DateTime @default(now())
+}