docs: enhance README with comprehensive documentation

[zchalmers]

This PR significantly enhances the README.md with:

Major Improvements:

• Better organization and structure with clear sections
• Comprehensive feature list highlighting the unique Unity visualization
• Detailed architecture overview
• Complete installation and setup instructions
• API endpoint documentation with examples
• Full project structure breakdown
• Deployment instructions (dev, CI/CD pipeline)
• Unity visualization details and usage

Enhanced Content:

• Step-by-step usage guide for both web and Unity interfaces
• Development tips and debugging guidance
• Configuration details for all templates
• Testing instructions
• Security best practices
• Visual formatting with emojis for better readability

What's New:

• Detailed Unity aquarium visualization explanation
• CI/CD pipeline creation and teardown instructions
• Local development setup guide
• Comprehensive technology stack section
• Contributing guidelines

The enhanced README transforms the project documentation from basic to professional, making it easy for developers to understand, set up, and contribute to this innovative stock visualization system.