FIX(db): update Prisma provider to PostgreSQL

- Change Prisma provider from mysql to postgresql
- Fix database configuration

services/nextjs/prisma/schema.prisma

@@ -6,7 +6,7 @@ generator client {
 }
 
 datasource db {
-  provider = "mysql"
+  provider = "postgresql"
   url      = env("DATABASE_URL")
 }