Add comprehensive development and deployment documentation

- Created DEVELOPMENT_DEPLOYMENT_GUIDE.md with detailed instructions for:
  * Dev container setup and local development workflow
  * Production server installation and configuration on Digital Ocean
  * Testing procedures for both environments
  * Deployment process with deploy.sh script
  * Troubleshooting common issues
  * Django 4.2 LTS upgrade details and new project structure

- Updated README.md to reference the new comprehensive guide
- Includes specific commands, directory structures, and step-by-step processes
- Covers both Python 3.11.13 dev container and production server workflows

Author: hburgund