Add support for monthly check-Ins and email reminders

[Madhawa97]

Description: Implement backend functionality to handle monthly check-ins and send email reminders.

Tasks:

• Design and implement database schema for check-in data.
• Create API endpoints for submitting and retrieving check-in data.
• Implement scheduling system for email reminders.
• Develop email templates for check-in reminders.
• Implement logic to track check-in submissions.

Acceptance Criteria:

• [ ] Design and implement a database schema for storing check-in data
• [ ] Create API endpoints for submitting and retrieving check-in data
• [ ] Implement a scheduling system for email reminders (consider using a job queue like Bull)
• [ ] Develop email templates for check-in reminders
• [ ] Implement logic to track which users have submitted their check-ins

Additional Information: Add additional information

Later:

• Create an API for users to manage their reminder preferences.

Related Dependencies or References: Add related dependencies and references relating to the implementation.