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
- Implemented SMTP client utilities in `test/helpers/smtp.client.ts` for creating test clients, sending emails, and testing connections.
- Developed SMTP protocol test utilities in `test/helpers/utils.ts` for managing TCP connections, sending commands, and handling responses.
- Created a detailed README in `test/readme.md` outlining the test framework, infrastructure, organization, and running instructions.
- Ported CMD-01: EHLO Command tests in `test/suite/smtpserver_commands/test.cmd-01.ehlo-command.test.ts` with multiple scenarios including valid and invalid hostnames.
- Ported CMD-02: MAIL FROM Command tests in `test/suite/smtpserver_commands/test.cmd-02.mail-from.test.ts` covering valid address acceptance, invalid address rejection, SIZE parameter support, and command sequence enforcement.
