Fix/es6 services - Refactor: Migrate All Services to ES Modules

[agaesh]

Overview

This pull request refactors multiple service files to fully adopt ES Module syntax (import/export) and improves overall code structure, consistency, and error handling across the service layer.

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🔧 Refactored Services

• DepartmentServices
• InstructorServices
• ProgramCourseServices
• StudentService
• UserService

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🧠 Key Improvements

• Migrated from CommonJS (require, module.exports) → ES Modules (import, export)
• Enhanced error handling and standardized error messages
• Improved code readability and consistency in naming conventions
• Simplified async function structures and return formats
• Ensured proper model initialization with sequelize and DataTypes

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✅ Next Step: Test each route endpoint to ensure compatibility and fix potential import path issues.

[agaesh]

✅ Issue Closed — Service Layer ES6 Refactor Completed

All service files have been successfully migrated to ES Module syntax for consistency with the rest of the codebase.
This update modernizes the structure of the following files without altering business logic or functionality:

DepartmentService.js

InstructorService.js

ProgramService.js

StudentService.js

UserService.js

Testing and verification will be handled later under the ES6 Migration branch.
Closing this issue as the refactor task is complete.