Fix/ES6 Migration: Complete CommonJS → ES6 Module Refactor

[agaesh]

🚀 Refactor: Migrate Codebase from CommonJS to ES6 Module

Overview

This PR completes the migration of the backend codebase from CommonJS (require/module.exports) to ES6 module syntax (import/export). The refactor improves consistency, maintainability, and alignment with modern Node.js standards.

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✨ Key Changes

🔁 ES6 Module Migration

• Migrated models, controllers, services, routes, middleware, validators, config, DB setup, tests, migrations, and seeders to ES module syntax.
• Added "type": "module" to package.json to enable native ES module support.

🧩 Models

• Migrated all Sequelize models to ES modules.
• Improved model loading structure.
• Fixed: Enabled timestamps for the Department model.

🧠 Controllers & Services

• Refactored all controllers and services to ES modules.
• Improved CRUD method structure and error handling.
• Unified export patterns for better readability and consistency.
• Streamlined authentication logic (cookie/token handling).

🌐 Routes

• Converted all route files to ES6 module syntax.
• Improved clarity and organization.

⚙️ Config & Database

• Migrated configuration and database setup to ES modules.
• Fixed case-sensitivity issues (config → Config) to prevent cross-platform bugs.
• Standardized import paths for db.js and config files.

🧪 Tests

• Updated unit and integration tests to ES module syntax.
• Improved test structure and error handling.
• Removed legacy CommonJS test files and added updated .test.js equivalents.

📦 Migrations & Seeders

• Migrated all Sequelize migration and seeder files to ES6 module syntax.
• Ensured compatibility with updated Sequelize configuration.

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✅ Benefits

• Modern, standardized module system
• Improved readability and maintainability
• Reduced platform-specific issues
• Cleaner exports and architecture consistency
• Better test organization and reliability

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📝 Notes

• No functional business logic changes intended beyond minor fixes and cleanups.
• This PR lays the groundwork for easier future upgrades and tooling support.

[agaesh]

This pull request completes the migration of the codebase from CommonJS to ES6 module syntax.
It refactors models, controllers, services, routes, middleware, config, tests, migrations, and seeders to use import/export, ensuring consistency across the project.

The changes improve code readability, maintainability, and alignment with modern Node.js standards.
Minor fixes and cleanups (such as path casing issues, export unification, and model timestamp configuration) are included as part of the refactor.

No breaking business-logic changes are intended.