Feature/es6 controllers

[agaesh]

🧩 Pull Request Title

feat(controllers): migrate all controllers to ES6 modules

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📝 Description

This PR converts all existing controller files from CommonJS (require/module.exports) to ES6 module syntax (import/export) to align with modern JavaScript standards and improve maintainability.

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✅ Controllers Updated

• DepartmentController.js
• InstructorController.js
• ProgramCourseController.js
• UserController.js

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🔄 Changes Made

• Replaced require with import and module.exports with export syntax.
• Implemented fileURLToPath for handling __dirname in ES modules.
• Cleaned up unused imports and improved function naming consistency.
• Standardized error handling and response formatting across all controllers.
• Ensured model imports use proper initialization with sequelize and DataTypes.

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🧠 Context

Part of the ES6 Migration Initiative to fully transition the backend architecture to modern ECMAScript standards for better compatibility with tools like Vite, Vitest, and ESLint.

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🧪 Testing

• Verified all routes for each controller are functional.
• No breaking changes detected in response formats.
• Successfully passed integration tests with database and services.

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🚀 Next Steps

• Proceed with ES6 conversion for Models and Services in separate PRs.
• Update documentation and import paths in routes once all modules are migrated.

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Would you like me to make a GitHub Issue description version of this too (to link with this PR)?