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/index.ts

@@ -0,0 +1,19 @@
+// Export all mail modules for simplified imports
+export * from './routing/index.ts';
+export * from './security/index.ts';
+
+// Make the core and delivery modules accessible
+import * as Core from './core/index.ts';
+import * as Delivery from './delivery/index.ts';
+
+export { Core, Delivery };
+
+// For direct imports
+import { Email } from './core/classes.email.ts';
+import { DcRouter } from '../classes.dcrouter.ts';
+
+// Re-export commonly used classes
+export {
+  Email,
+  DcRouter
+};