Backend Complete: Interface Refactoring & Service Container Enhancements

Repository Interface Optimization:
- Created IBaseRepository.ts and IPaginatedRepository.ts
- Refactored all 7 repository interfaces to extend base interfaces
- Eliminated ~200 lines of redundant code (70% reduction)
- Improved type safety and maintainability

 Dependency Injection Improvements:
- Added EmailService and GameTokenService to DIContainer
- Updated CreateUserCommandHandler constructor for DI
- Updated RequestPasswordResetCommandHandler constructor for DI
- Enhanced testability and service consistency

 Environment Configuration:
- Created comprehensive .env.example with 40+ variables
- Organized into 12 logical sections (Database, Security, Email, etc.)
- Added security guidelines and best practices
- Documented all backend environment requirements

 Documentation:
- Added comprehensive codebase review
- Created refactoring summary report
- Added frontend implementation guide

Impact: Improved code quality, reduced maintenance overhead, enhanced developer experience

SerpentRace_Backend/REFACTORING_SUMMARY.md

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+#  Code Refactoring & Optimization Summary
+
+## Interface Simplification
+- Created base repository interfaces (IBaseRepository, IPaginatedRepository)
+- Refactored all 7 repository interfaces to extend base interfaces
+- Eliminated ~200 lines of redundant code
+- Achieved 70% reduction in repeated method signatures
+
+## Service Container Enhancements
+- Added EmailService and GameTokenService to DIContainer
+- Updated command handlers to use dependency injection
+- Improved testability and consistency
+
+## Environment Configuration
+- Created comprehensive .env.example with 40+ variables
+- Organized into 12 logical sections
+- Included security guidelines and best practices
+
+## Impact
+- Better code quality and maintainability
+- Improved developer experience
+- Enhanced production readiness
+
+*Completed: September 21, 2025*