fix(schema): revert datasource URL, add Group.accountId index

apps/api/prisma/migrations/20260527113943_add_group_account_index/migration.sql

@@ -0,0 +1,2 @@
+-- CreateIndex
+CREATE INDEX "Group_accountId_idx" ON "Group"("accountId");

apps/api/prisma/schema.prisma

@@ -4,7 +4,7 @@ generator client {
 
 datasource db {
   provider = "postgresql"
-  url      = env("../../../DATABASE_URL")  
+  url      = env("DATABASE_URL")
 }
 
 model Group {
@@ -25,6 +25,7 @@ model Group {
   consentRecords ConsentRecord[]
 
   @@unique([platform, platformId])
+  @@index([accountId])
 }
 
 model Message {