feat(rust): scaffold Rust workspace and fix TypeScript build errors

- Add @git.zone/tsrust with linux_amd64/linux_arm64 cross-compilation
- Scaffold Rust workspace with 5 crates: mailer-core, mailer-smtp, mailer-security, mailer-napi, mailer-bin
- Fix all TypeScript compilation errors for upgraded dependencies (smartfile v13, mailauth v4.13, smartproxy v23)
- Replace smartfile.fs/memory with @push.rocks/smartfs throughout codebase
- Fix .ts import extensions to .js for NodeNext module resolution
- Update DKIMSignOptions usage to match mailauth v4.13 API
- Add MTA error classes with permissive signatures for legacy SMTP client
- Replace removed DcRouter/StorageManager/deliverability imports with local interfaces

ts/mail/core/classes.email.ts

@@ -1,5 +1,5 @@
-import * as plugins from '../../plugins.ts';
-import { EmailValidator } from './classes.emailvalidator.ts';
+import * as plugins from '../../plugins.js';
+import { EmailValidator } from './classes.emailvalidator.js';
 
 export interface IAttachment {
   filename: string;
@@ -614,10 +614,11 @@ export class Email {
     
     // Add attachments
     for (const attachment of this.attachments) {
-      const smartAttachment = await plugins.smartfile.SmartFile.fromBuffer(
-        attachment.filename,
-        attachment.content
-      );
+      const smartAttachment = new plugins.smartfile.SmartFile({
+        path: attachment.filename,
+        contentBuffer: attachment.content,
+        base: process.cwd(),
+      });
       
       // Set content type if available
       if (attachment.contentType) {