Fix/es6 controllers

[agaesh]

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🧱 Pull Request: Refactor Controllers to ES Module Syntax

Overview

This PR completes the migration of all controller files from CommonJS to ES Module (ESM) syntax.
The goal is to ensure full compatibility with modern Node.js environments and align with the ongoing ES6 refactor initiative across the codebase.

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Controllers Updated

• ✅ DepartmentController — migrated and optimized CRUD functions
• ✅ InstructorController — cleaned and reorganized create/update logic
• ✅ ProgramCourseController — standardized imports and refactored handlers
• ✅ UserController — improved function structure and cookie management

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Improvements

• Unified syntax using import / export
• Simplified function structures for better readability
• Enhanced code consistency across all controllers
• Prepared controllers for upcoming ESM-based service integrations

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Next Steps

• Refactor corresponding service and route layers

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Summary:
All controllers are now fully ESM-compliant and ready for integration testing.
This refactor modernizes the project structure and reduces potential module resolution conflicts.