Add Resend and Breveo Mailing Services (Loadbalancing possible)

## Backend Feature

I suggest adding **Resend** and **Brevo** mailer clients to the **backend** Utils.
These clients will allow the backend to send transactional or notification emails using either service.

It can be a good option to add for future use.

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## What is to be done.
1. **Create a `Mailers/` directory** in the Next.js project (under `/lib`).
2. Create the **Clients** for Brevo and Resend
3. **Integrate with API routes**: - Create a test API route like `api/sendmail` that calls one or both mailers (_possible load balancing_).
- Route should accept JSON body: `{ "to": "email@example.com", "subject": "Test", "html": "

Hello

" }`.
- Return JSON with the success/error result from the mailer function.
- Proper HTTP responses to be captured
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## Related

- Future backend notifications and alerting features.
- Linked to system monitoring or admin alert enhancements.
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**Please consider this Issue for Hacktoberfest, and I would love to work on this**
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