chore(tests): add missing schema.zmodel for ext-result tests

Add the source .zmodel file so the generated schema.ts can be
regenerated, matching the convention used by sibling test directories.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: genu

tests/e2e/orm/plugin-infra/ext-result/schema.zmodel

@@ -0,0 +1,17 @@
+datasource db {
+    provider = "sqlite"
+}
+
+model User {
+    id    Int    @id @default(autoincrement())
+    name  String
+    posts Post[]
+}
+
+model Post {
+    id       Int     @id @default(autoincrement())
+    title    String
+    content  String?
+    author   User    @relation(fields: [authorId], references: [id])
+    authorId Int
+}