Initial scaffold: unified customer/insurance/utilities platform

Next.js + NestJS + Prisma (MySQL) monorepo replacing the legacy PHP
internal app. Includes a session-based auth module with Argon2 password
hashing and global input validation (replacing the old app's SQL
injection and plaintext password comparison), the full target Prisma
schema for customers/insurance/utilities/shared ledger/bank register,
Docker Compose + Dockerfiles, and an Access-to-staging migration
pipeline (migration/) already run against the real source databases.

See PLAN.md and RESUME.md for the full architecture and session history.

apps/api/src/users/users.service.ts

@@ -0,0 +1,16 @@
+import { Injectable } from "@nestjs/common";
+import { PrismaService } from "../prisma/prisma.service";
+import type { User } from "@jorgecuadros/database";
+
+@Injectable()
+export class UsersService {
+  constructor(private readonly prisma: PrismaService) {}
+
+  findByEmail(email: string): Promise<User | null> {
+    return this.prisma.user.findUnique({ where: { email } });
+  }
+
+  findById(id: string): Promise<User | null> {
+    return this.prisma.user.findUnique({ where: { id } });
+  }
+}