Added a setup.md as per owner specification

setup.md

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+# Project Setup Guide
+
+Welcome to the D3Flo Invoice Intelligence Platform! This guide walks you through the full setup required to run the application locally or in a development environment.
+
+--- 
+## Prerequisites
+Ensure you have the following installed:
+
+*  **Node.js** ≥ v18+
+
+*  **pnpm** ≥ v8+
+
+Install it with:
+```
+npm install -g pnpm
+```
+
+* PostgreSQL or compatible DB (used by Prisma)
+---
+## Directory Structure Overview
+
+```
+/app             - App routes, API, UI components
+/components      - Reusable UI elements
+/lib             - Utilities (CSV export, invoice agents)
+/trpc            - Backend procedures and logic
+/styles          - Tailwind and global styles
+```
+---
+
+## Getting started
+### 1. Clone the reporsitory
+```
+git clone <your-repo-url>
+cd your-project
+```
+### 2. Install dependencies
+```
+pnpm install
+```
+### 3. Set up your environment variables
+Create a `.env` file at the root of your project. You can copy from `.env.example` if provided, and define the following:
+```
+DATABASE_URL=postgresql://user:password@localhost:5432/dbname
+LANGBASE_API_KEY=your_langbase_key
+GOOGLE_API_KEY=your_google_api_key
+ARCJET_KEY=your_arcjet_key
+```
+### 4. Run the database migration
+```
+npx prisma migrate dev --name init
+```
+You can also introspect the existing DB schema if needed:
+```
+npx prisma db pull
+```
+### 5. Start the development server
+```
+pnpm dev
+```
+
+Visit [Preview Website](http://localhost:3000) to view the app.
+
+---
+
+## Key Features
+### 1. Invoice Intelligence (AI-powered)
+Located in `/lib/invoiceAgent.ts`
+
+* Extracts structured data from invoice text
+* Performs financial insights analysis
+* Auto-generates payment reminder emails using Gemini 2.0 via Langbase
+
+### 2. CSV Export Utility
+Found in `lib/downloadCSV.ts`
+
+* Converts arrays of invoice data into CSV
+* Adds timestamped filenames
+* Displays toast notifications using `sonner`
+
+### 3. API Rate Limiting
+Uses `@arcjet/next` in `lib/` and `trpc/`:
+* Based on IP (`ip.src`)
+* Token bucket model (10 requests/hour)
+
+---
+## Tooling & Configuration:
+ESLint (`.eslintrc.json`)
+* Uses `next/core-web-vitals` config
+* Custom rules for TS usage and relaxed JSX handling
+
+TypeScript (`tsconfig.json`)
+* Strict mode enabled
+* JSX support (`preserve`)
+* Modern module resolution
+* Path aliasing (`@/*` → `./*`)
+
+---
+## Quality & Linting
+Run lint checks:
+```
+pnpm lint
+```
+
+Or auro-fix:
+```
+pnpm lint --fix
+```
+
+---
+## Deployment
+
+You can deploy to Vercel, Netlify, or any Node-compatible environment. Make sure to configure all `.env` variables in your hosting provider's dashboard.
+
+---
+
+## Aditional Notes
+* Uses `tailwind-merge` and `clsx` for clean class name composition
+* Generates consistent section IDs with `createSectionId` helper
+* Prisma Client and database utils found under `app/utils/db.ts`
+
+## Licences
+MIT License – free to use and modify.