fix(readme): Update readme with consolidated email system improvements and modular directory structure

Clarify that the platform now organizes email functionality into distinct directories (mail/core, mail/delivery, mail/routing, mail/security, mail/services) and update the diagram and key features list accordingly. Adjust code examples to reflect explicit module imports and the use of SzPlatformService.

ts/00_commitinfo_data.ts

@@ -3,6 +3,6 @@
  */
 export const commitinfo = {
   name: '@serve.zone/platformservice',
-  version: '2.8.0',
+  version: '2.8.1',
   description: 'A multifaceted platform service handling mail, SMS, letter delivery, and AI services.'
 }