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/delivery/smtpclient/auth-handler.ts

@@ -3,22 +3,22 @@
  * Authentication mechanisms implementation
  */
 
-import { AUTH_METHODS } from './constants.ts';
+import { AUTH_METHODS } from './constants.js';
 import type { 
   ISmtpConnection, 
   ISmtpAuthOptions, 
   ISmtpClientOptions,
   ISmtpResponse,
   IOAuth2Options
-} from './interfaces.ts';
+} from './interfaces.js';
 import { 
   encodeAuthPlain, 
   encodeAuthLogin, 
   generateOAuth2String,
   isSuccessCode 
-} from './utils/helpers.ts';
-import { logAuthentication, logDebug } from './utils/logging.ts';
-import type { CommandHandler } from './command-handler.ts';
+} from './utils/helpers.js';
+import { logAuthentication, logDebug } from './utils/logging.js';
+import type { CommandHandler } from './command-handler.js';
 
 export class AuthHandler {
   private options: ISmtpClientOptions;