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/src/Application/DTOs/Mappers/UserMapper.ts

@@ -0,0 +1,32 @@
+import { UserAggregate, UserState } from '../../../Domain/User/UserAggregate';
+import { CreateUserDto, UpdateUserDto, ShortUserDto, DetailUserDto } from '../UserDto';
+import { BaseMapper } from './BaseMapper';
+
+export class UserMapper {
+  static toShortDto(user: UserAggregate): ShortUserDto {
+    return {
+      id: user.id,
+      username: user.username,
+      state: user.state,
+      authLevel: (user.state === UserState.ADMIN ? 1 : 0) as 0 | 1,
+    };
+  }
+
+  static toDetailDto(user: UserAggregate): DetailUserDto {
+    return {
+      id: user.id,
+      orgid: user.orgid,
+      username: user.username,
+      email: user.email,
+      fname: user.fname,
+      lname: user.lname,
+      code: user.token,
+      phone: user.phone,
+      state: user.state,
+    };
+  }
+
+  static toShortDtoList(users: UserAggregate[]): ShortUserDto[] {
+    return BaseMapper.toShortDtoListStatic(users, UserMapper.toShortDto);
+  }
+}