fix: use standalone prisma.config.js to avoid runtime module errors

prisma.config.js

@@ -0,0 +1,10 @@
+/**
+ * Prisma 7 Configuration
+ * In standalone Docker mode, devDependencies are missing.
+ * This file uses a plain object to avoid 'Cannot find module' errors.
+ */
+export default {
+  datasource: {
+    url: process.env.DATABASE_URL,
+  },
+};