feat(email): add sender email to sendOtpEmail

- Added `senderEmail` parameter.
- Updated documentation.
- Improved function clarity.

Author: fulleni

lib/src/ht_email_repository.dart

@@ -23,19 +23,22 @@ class HtEmailRepository {
   /// constructs the required `templateData` and calls the generic
   /// `sendTransactionalEmail` method on the injected [HtEmailClient].
   ///
+  /// - [senderEmail]: The email address of the sender.
   /// - [recipientEmail]: The email address of the recipient.
   /// - [otpCode]: The One-Time Password to be sent.
   /// - [templateId]: The ID of the transactional email template to use.
   ///
   /// Throws [HtHttpException] subtypes on failure, as propagated from the
   /// client.
   Future<void> sendOtpEmail({
+    required String senderEmail,
     required String recipientEmail,
     required String otpCode,
     required String templateId,
   }) async {
     try {
       await _emailClient.sendTransactionalEmail(
+        senderEmail: senderEmail,
         recipientEmail: recipientEmail,
         templateId: templateId,
         templateData: {'otp_code': otpCode},