feat(storage): add comprehensive tests for StorageManager with memory, filesystem, and custom function backends

feat(email): implement EmailSendJob class for robust email delivery with retry logic and MX record resolution

feat(mail): restructure mail module exports for simplified access to core and delivery functionalities

ts/mail/delivery/smtpclient/smtp-client.ts

@@ -3,7 +3,7 @@
  * Main client class with delegation to handlers
  */
 
-import * as plugins from '../../../plugins.ts';
+import { EventEmitter } from 'node:events';
 import type { Email } from '../../core/classes.email.ts';
 import type { 
   ISmtpClientOptions,
@@ -30,7 +30,7 @@ interface ISmtpClientDependencies {
   errorHandler: SmtpErrorHandler;
 }
 
-export class SmtpClient extends plugins.EventEmitter {
+export class SmtpClient extends EventEmitter {
   private options: ISmtpClientOptions;
   private connectionManager: ConnectionManager;
   private commandHandler: CommandHandler;