Created Authentication API using JWT and added Serializers for the models

[wra-wtag]

Authentication API using JWT and Model Serializers

Trello Ticket: Authentication API using JWT and Model Serializers

Description

Implements JWT-based authentication for secure API access and adds serializers for uniform JSON data across all major models.
This enhances API security, consistency, and usability for external integrations and frontend clients.

Changes

• Created Authentication API using JWT (login, signup, token validation)
• Added Serializers for User, Job, Company, Application, and Profile models
• Implemented API Controllers for applications, jobs, companies, and profiles
• Secured all API routes behind JWT-based authorization filters
• Wrote RSpec tests for authentication and core API endpoints
• Fixed minor syntax issues and improved API response consistency
• Verified compatibility with existing notification and dashboard modules

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