feat: add repository pattern, service layer architecture, and scheduler management

- Implement repository pattern for data access layer
- Add comprehensive service layer for business logic
- Create scheduler management system with health monitoring
- Add bounded buffer utility for memory management
- Enhance security audit logging with retention policies

lib/auditLogScheduler.ts

@@ -1,4 +1,4 @@
-import cron from "node-cron";
+import * as cron from "node-cron";
 import { executeScheduledRetention } from "./auditLogRetention";
 import {
   AuditOutcome,
@@ -8,7 +8,7 @@ import {
 } from "./securityAuditLogger";
 
 export class AuditLogScheduler {
-  private retentionTask: any = null;
+  private retentionTask: cron.ScheduledTask | null = null;
   private isRunning = false;
 
   constructor() {
@@ -130,7 +130,7 @@ export class AuditLogScheduler {
   } {
     return {
       isRunning: this.isRunning,
-      nextExecution: this.retentionTask?.getStatus()?.next || undefined,
+      nextExecution: undefined, // node-cron doesn't provide next execution time
       schedule: process.env.AUDIT_LOG_RETENTION_SCHEDULE || "0 2 * * 0",
     };
   }