fix: remove url from schema datasource (Prisma 7.x)

Prisma 7.x no longer supports 'url' in the schema datasource block.
The URL is provided exclusively via prisma.config.ts.

prisma/schema.prisma

@@ -4,7 +4,6 @@ generator client {
 
 datasource db {
   provider = "postgresql"
-  url      = env("DATABASE_URL")
 }
 
 // ───────────────────────────────────────