User Story
As a new user signing up for Paycrest
I want to receive a welcome email after successful registration
So that I can feel welcomed and understand what type of account I've created

Acceptance Criteria

1. GIVEN a user successfully registers on Paycrest
   WHEN the registration process completes
   THEN a welcome email should be sent to their email address

2. GIVEN a user registers with either sender or provider scope
   WHEN the welcome email is received
   THEN it should contain information specific to their account type

3. GIVEN a user registers in any environment (production/non-production)
   WHEN the registration is successful
   THEN the welcome email should be sent regardless of email verification status

Tech Details

1. Create new SendGrid template for welcome emails with dynamic data:

   • first_name: User's first name
   • email: User's email address
   • scopes: User's account scopes (sender/provider)

2. Add new method to EmailService:

func (m *EmailService) SendWelcomeEmail(ctx context.Context, email, firstName string, scopes []string) (types.SendEmailResponse, error) {
    payload := types.SendEmailPayload{
        FromAddress: _DefaultFromAddress,
        ToAddress:   email,
        DynamicData: map[string]interface{}{
            "first_name": firstName,
            "email":     email,
            "scopes":    scopes,
        },
    }
    return SendTemplateEmail(payload, "WELCOME_EMAIL_TEMPLATE_ID")
}

3. Modify Register function in controllers/accounts/auth.go to send welcome email after successful user creation but before verification email.

4. Add unit tests in services/email_test.go and integration tests in controllers/accounts/auth_test.go.

Notes/Assumptions

• The welcome email should be sent after user creation but before verification email
• If welcome email fails to send, it should be logged but not block registration
• Existing email service infrastructure (SendGrid) will be used
• Welcome email template will be created in SendGrid before implementation
• The feature should not affect existing email verification flow