feat: implement comprehensive route-based email routing system

Replace legacy domain-rule based routing with flexible route-based system that supports:
- Multi-criteria matching (recipients, senders, IPs, authentication)
- Four action types (forward, process, deliver, reject)
- Moved DKIM signing to delivery phase for signature validity
- Connection pooling for efficient email forwarding
- Pattern caching for improved performance

This provides more granular control over email routing with priority-based matching and comprehensive test coverage.

ts/mail/delivery/classes.delivery.queue.ts

@@ -3,7 +3,8 @@ import { EventEmitter } from 'node:events';
 import * as fs from 'node:fs';
 import * as path from 'node:path';
 import { logger } from '../../logger.js';
-import { type EmailProcessingMode, type IDomainRule } from '../routing/classes.email.config.js';
+import { type EmailProcessingMode } from '../routing/classes.email.config.js';
+import type { IEmailRoute } from '../routing/interfaces.js';
 
 /**
  * Queue item status
@@ -17,7 +18,7 @@ export interface IQueueItem {
   id: string;
   processingMode: EmailProcessingMode;
   processingResult: any;
-  rule: IDomainRule;
+  route: IEmailRoute;
   status: QueueItemStatus;
   attempts: number;
   nextAttempt: Date;
@@ -218,9 +219,9 @@ export class UnifiedDeliveryQueue extends EventEmitter {
    * Add an item to the queue
    * @param processingResult Processing result to queue
    * @param mode Processing mode
-   * @param rule Domain rule
+   * @param route Email route
    */
-  public async enqueue(processingResult: any, mode: EmailProcessingMode, rule: IDomainRule): Promise<string> {
+  public async enqueue(processingResult: any, mode: EmailProcessingMode, route: IEmailRoute): Promise<string> {
     // Check if queue is full
     if (this.queue.size >= this.options.maxQueueSize) {
       throw new Error('Queue is full');
@@ -234,7 +235,7 @@ export class UnifiedDeliveryQueue extends EventEmitter {
       id,
       processingMode: mode,
       processingResult,
-      rule,
+      route,
       status: 'pending',
       attempts: 0,
       nextAttempt: new Date(),