refactor(emails): restructure email system and add recording notifications

- Move email templates to separate files in src/emails/templates/
- Create new email service architecture (service.js, index.js)
- Add recording suggestions email template for matching notifications
- Integrate email notifications with matching system (sends when suggestions created)
- Update controllers (auth.js, user.js) to use new email module
- Update tests to use new email module path
- Remove deprecated src/utils/email.js

Features:
- Template-based email system for easy editing
- Automatic email notifications when recording assignments are made
- Clean separation between template logic and sending logic
- Graceful error handling for AWS SES failures

backend/src/controllers/auth.js

@@ -7,7 +7,7 @@ const {
   generateVerificationCode,
   getTokenExpiry
 } = require('../utils/auth');
-const { sendVerificationEmail, sendWelcomeEmail, sendPasswordResetEmail } = require('../utils/email');
+const { sendVerificationEmail, sendWelcomeEmail, sendPasswordResetEmail } = require('../emails');
 const { sanitizeForEmail, timingSafeEqual } = require('../utils/sanitize');
 const securityConfig = require('../config/security');
 

backend/src/controllers/user.js

@@ -1,6 +1,6 @@
 const { prisma } = require('../utils/db');
 const { hashPassword, comparePassword, generateToken, generateVerificationToken, generateVerificationCode } = require('../utils/auth');
-const { sendVerificationEmail } = require('../utils/email');
+const { sendVerificationEmail } = require('../emails');
 const { sanitizeForEmail } = require('../utils/sanitize');
 
 /**