Fix numpy import error and improve development setup

[crackerky]

🐛 Problem

Users were encountering ImportError: numpy.core.multiarray failed to import when trying to run the receipt scanner due to Python package conflicts and missing dependencies.

✅ Solution

This PR fixes the numpy import error and significantly improves the development setup experience.

Changes Made

1. Environment Configuration

   • Updated .env to use SQLite by default (no PostgreSQL required for development)
   • Made OpenAI API key optional (OCR-only mode works without it)
   • Improved configuration comments for clarity

2. Dependency Management

   • Added instructions for virtual environment setup
   • Fixed numpy compatibility issues
   • Resolved frontend security vulnerabilities with npm audit fix

3. Development Experience

   • Simplified setup process - no external services required
   • Works out-of-the-box with just Tesseract OCR installed
   • Better error handling for missing dependencies

📋 Setup Instructions

# Backend setup
cd receipt-scanner-app/receipt-scanner-backend
python3 -m venv venv
source venv/bin/activate
pip install -r requirements.txt
pip install email-validator  # Additional dependency
python init_db.py

# Frontend setup  
cd ../receipt-scanner-frontend
npm install
npm audit fix

🧪 Testing

• Virtual environment resolves numpy import error
• Backend starts successfully without OpenAI API key
• OCR processing works with Tesseract only
• Database initializes with SQLite
• Frontend builds without vulnerabilities

📝 Notes

• This makes the project much more accessible for new developers
• No API keys or external services needed to get started
• OCR-only mode provides basic functionality without AI features

Fixes common setup issues reported by users.

🤖 Generated with Claude Code

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