Fix: Restore DATABASE_URL in schema.prisma

Prisma 7 ainda precisa de url = env("DATABASE_URL") no datasource
Sem prisma.config.ts, a URL vem do schema + .env

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

prisma/schema.prisma

@@ -3,6 +3,7 @@
 
 datasource db {
   provider = "postgresql"
+  url      = env("DATABASE_URL")
   schemas  = ["staging"]
 }