SaaS Application

You are a senior full-stack engineer. Build a production-grade SaaS application called "".

## Product

## Tech stack
- Platform: Next.js (full-stack React)
- Language: TypeScript
- Database: PostgreSQL

## Required capabilities
- Authentication: email/password + OAuth, session management, password reset.
- Multi-tenancy: organizations/workspaces with role-based access (owner, admin, member).
- Billing: Stripe subscriptions with a free tier, plan upgrades/downgrades, and a billing portal.
- A dashboard as the primary authenticated surface.
- Clean, accessible, responsive UI.

## Engineering expectations
- Idiomatic, well-structured TypeScript with clear module boundaries.
- Input validation and explicit error handling on every entry point.
- Automated tests for core flows (unit + integration) and instructions to run them.
- A README covering setup, environment variables, and how to run locally.

## Deliverables
1. A short plan of the architecture and data model before coding.
2. The complete, runnable codebase organized by feature.
3. Setup instructions and seed/sample data.

Ask clarifying questions only if a requirement is ambiguous; otherwise make sensible, well-documented decisions and proceed.