A personal finance tracking API built with NestJS and PostgreSQL. Designed both as a practical tool for managing personal expenses and as a showcase of serious backend architecture patterns.

• User registration (POST /auth/signup) with email/password validation
• Password hashing with Argon2
• Duplicate email detection — Prisma P2002 → 403 ForbiddenException
• User signin (POST /auth/signin) — credential lookup + Argon2 verify
• Global ValidationPipe with whitelist (strips unexpected fields)
• Prisma ORM integration with PostgreSQL
• Database schema: users and expenses tables with relations
• Expense table indexes on userId and date for query performance
• Docker Compose setup for local development database
• Empty module scaffolding: UserModule, ExpenseModule

• JWT access token returned on signin (@nestjs/jwt…