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/security/index.ts

@@ -3,7 +3,7 @@ export {
   SecurityLogLevel,
   SecurityEventType,
   type ISecurityEvent
-} from './classes.securitylogger.ts';
+} from './classes.securitylogger.js';
 
 export {
   IPReputationChecker,
@@ -11,11 +11,11 @@ export {
   IPType,
   type IReputationResult,
   type IIPReputationOptions
-} from './classes.ipreputationchecker.ts';
+} from './classes.ipreputationchecker.js';
 
 export {
   ContentScanner,
   ThreatCategory,
   type IScanResult,
   type IContentScannerOptions
-} from './classes.contentscanner.ts';
+} from './classes.contentscanner.js';