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/repositories/RepositoryFactory.ts

@@ -0,0 +1,92 @@
+import { SecurityAuditLogRepository } from "./SecurityAuditLogRepository";
+import { SessionRepository } from "./SessionRepository";
+import { UserRepository } from "./UserRepository";
+
+/**
+ * Repository factory for centralized repository management
+ * Implements singleton pattern to ensure single instances
+ */
+export class RepositoryFactory {
+  private static instance: RepositoryFactory;
+
+  private sessionRepository?: SessionRepository;
+  private userRepository?: UserRepository;
+  private securityAuditLogRepository?: SecurityAuditLogRepository;
+
+  private constructor() {
+    // Private constructor for singleton
+  }
+
+  /**
+   * Get the singleton instance of RepositoryFactory
+   */
+  static getInstance(): RepositoryFactory {
+    if (!RepositoryFactory.instance) {
+      RepositoryFactory.instance = new RepositoryFactory();
+    }
+    return RepositoryFactory.instance;
+  }
+
+  /**
+   * Get SessionRepository instance
+   */
+  getSessionRepository(): SessionRepository {
+    if (!this.sessionRepository) {
+      this.sessionRepository = new SessionRepository();
+    }
+    return this.sessionRepository;
+  }
+
+  /**
+   * Get UserRepository instance
+   */
+  getUserRepository(): UserRepository {
+    if (!this.userRepository) {
+      this.userRepository = new UserRepository();
+    }
+    return this.userRepository;
+  }
+
+  /**
+   * Get SecurityAuditLogRepository instance
+   */
+  getSecurityAuditLogRepository(): SecurityAuditLogRepository {
+    if (!this.securityAuditLogRepository) {
+      this.securityAuditLogRepository = new SecurityAuditLogRepository();
+    }
+    return this.securityAuditLogRepository;
+  }
+
+  /**
+   * Get all repository instances
+   */
+  getAllRepositories() {
+    return {
+      sessions: this.getSessionRepository(),
+      users: this.getUserRepository(),
+      securityAuditLogs: this.getSecurityAuditLogRepository(),
+    };
+  }
+
+  /**
+   * Reset all repository instances (useful for testing)
+   */
+  reset(): void {
+    this.sessionRepository = undefined;
+    this.userRepository = undefined;
+    this.securityAuditLogRepository = undefined;
+  }
+}
+
+/**
+ * Convenience function to get repository factory instance
+ */
+export const repositories = RepositoryFactory.getInstance();
+
+/**
+ * Convenience functions to get specific repositories
+ */
+export const getSessionRepository = () => repositories.getSessionRepository();
+export const getUserRepository = () => repositories.getUserRepository();
+export const getSecurityAuditLogRepository = () =>
+  repositories.getSecurityAuditLogRepository();