Fix build process and add production build support

🔧 Build Process Improvements:
- Update default 'build' target to use development mode
- Add new 'build-prod' target for production builds with validation
- Fix 'deploy-prod-quick' to use production build command
- Update 'build-test' to use development build (safer for CI)

📚 Documentation:
- Add comprehensive Production Build Guide (docs/deployment/PRODUCTION_BUILD.md)
- Include security requirements, configuration methods, and troubleshooting
- Update main documentation index with production build guide
- Update README with both build command options

✨ Features:
- Development builds work without security configuration
- Production builds require proper JWT/SESSION secrets
- Clear separation between dev and prod build processes
- Comprehensive production deployment documentation

🔒 Security:
- Enforced JWT_SECRET validation for production builds
- Clear documentation of required security configurations
- Examples for CI/CD integration with proper secret management
- Best practices for production deployment

🧪 Verification:
- ✅ Development build: make build (works with warnings)
- ✅ Production build validation: make build-prod (fails without secrets)
- ✅ Production build with secrets: works correctly
- ✅ All existing functionality preserved

README.md

@@ -150,7 +150,8 @@ make help
 
 # Quick development commands
 make start          # Start development server
-make build          # Build the application
+make build          # Build for development
+make build-prod     # Build for production (requires configuration)
 make test           # Run unit tests
 
 # Testing commands