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/BaseRepository.ts

@@ -0,0 +1,71 @@
+/**
+ * Base repository interface with common CRUD operations
+ */
+export interface BaseRepository<T, ID = string> {
+  findById(id: ID): Promise<T | null>;
+  findMany(options?: FindManyOptions<T>): Promise<T[]>;
+  create(data: CreateInput<T>): Promise<T>;
+  update(id: ID, data: UpdateInput<T>): Promise<T | null>;
+  delete(id: ID): Promise<boolean>;
+  count(options?: CountOptions<T>): Promise<number>;
+}
+
+/**
+ * Generic find options interface
+ */
+export interface FindManyOptions<T> {
+  where?: Partial<T>;
+  orderBy?: Record<keyof T, "asc" | "desc">;
+  skip?: number;
+  take?: number;
+  include?: Record<string, boolean>;
+}
+
+/**
+ * Generic count options interface
+ */
+export interface CountOptions<T> {
+  where?: Partial<T>;
+}
+
+/**
+ * Create input type - excludes auto-generated fields
+ */
+export type CreateInput<T> = Omit<T, "id" | "createdAt" | "updatedAt">;
+
+/**
+ * Update input type - excludes auto-generated fields and makes all optional
+ */
+export type UpdateInput<T> = Partial<Omit<T, "id" | "createdAt" | "updatedAt">>;
+
+/**
+ * Repository error types
+ */
+export class RepositoryError extends Error {
+  constructor(
+    message: string,
+    public readonly code: string,
+    public readonly cause?: Error
+  ) {
+    super(message);
+    this.name = "RepositoryError";
+  }
+}
+
+export class NotFoundError extends RepositoryError {
+  constructor(entity: string, id: string | number) {
+    super(`${entity} with id ${id} not found`, "NOT_FOUND");
+  }
+}
+
+export class ConflictError extends RepositoryError {
+  constructor(message: string, cause?: Error) {
+    super(message, "CONFLICT", cause);
+  }
+}
+
+export class ValidationError extends RepositoryError {
+  constructor(message: string, cause?: Error) {
+    super(message, "VALIDATION_ERROR", cause);
+  }
+}