feat(api): create a basic email sending service

[nullscribe]

Type of Task

Feature

User Story / Goal

As a developer, I want a single, reusable service for sending transactional emails so that all email logic is centralized and easy to manage.

Acceptance Criteria

• A new, generic EmailService module is created.
• It integrates with a transactional email provider (e.g., Resend, Mailgun) via their SDK.
• The service exposes a simple method, like sendEmail(to, subject, htmlBody).
• All necessary API keys and configuration are managed through environment variables.
• The service is successfully used by the email verification process.

Technical Breakdown (Optional)

No response

Affected Packages

api

Designs / Mockups (Optional)

No response