Write an LLMs.md file for AI to help it better understand the project and write better code for us.

## 1. Project Overview
- Project description
- Target users / business senarios
- A breif description of the tech stack (front-end, back-end, database, middleware, etc.)

## 2. Tech Stack & Architecture
- Front-end
- Back-end
- Database
- Architecture description/diagram
- Communication method

## 3. Modules & Features
- Responsibilities of each module

## 4. Directory Structure