Inform users when their message is received and send a confirmation email

Implements email confirmation functionality for contact messages using Nodemailer and updates the success message in ContactForm.tsx.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: 06e058c0-42ef-4e06-a856-f935107c7d32
Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/27368044-0fb0-4464-b2d1-6d418eeb23b8/06e058c0-42ef-4e06-a856-f935107c7d32/QkGxiV8
