perf: optimize portfolio queries and workflows

apps/api/src/database.ts

@@ -1,7 +1,24 @@
 import { Injectable, OnModuleInit, OnModuleDestroy } from '@nestjs/common';
-import { PrismaClient } from '@prisma/client';
+import { PrismaClient, Prisma } from '@prisma/client';
 @Injectable()
 export class Database extends PrismaClient implements OnModuleInit, OnModuleDestroy {
+  async serial<T>(work: (tx: Prisma.TransactionClient) => Promise<T>): Promise<T> {
+    for (let attempt = 0; ; attempt++) {
+      try {
+        return await this.$transaction(work, {
+          isolationLevel: Prisma.TransactionIsolationLevel.Serializable,
+        });
+      } catch (error) {
+        // Serializable deadlock/write conflict; retry the entire atomic operation.
+        const retryable =
+          error instanceof Prisma.PrismaClientKnownRequestError &&
+          (error.code === 'P2034' ||
+            (error.code === 'P2010' && ['1213', '1205'].includes(String(error.meta?.code))));
+        if (!retryable || attempt >= 3) throw error;
+        await new Promise((resolve) => setTimeout(resolve, 20 * 2 ** attempt + Math.random() * 20));
+      }
+    }
+  }
   async onModuleInit() {
     await this.$connect();
   }