feat(service): add Service and ServiceManager for component lifecycle management

Adds two new classes:
- Service: long-running component with start/stop lifecycle, health checks, builder pattern and subclass support
- ServiceManager: orchestrates multiple services with dependency-ordered startup, failure isolation, retry with backoff, and reverse-order shutdown

ts/index.ts

@@ -14,5 +14,22 @@ export type { ITaskStep } from './taskbuffer.classes.taskstep.js';
 // Metadata interfaces
 export type { ITaskMetadata, ITaskExecutionReport, IScheduledTaskInfo, ITaskEvent, TTaskEventType, ITaskConstraintGroupOptions, ITaskExecution, IRateLimitConfig, TResultSharingMode } from './taskbuffer.interfaces.js';
 
+// Service lifecycle system
+export { Service } from './taskbuffer.classes.service.js';
+export { ServiceManager } from './taskbuffer.classes.servicemanager.js';
+export type {
+  IServiceOptions,
+  IServiceStatus,
+  IServiceEvent,
+  IServiceManagerOptions,
+  IServiceManagerHealth,
+  IRetryConfig,
+  IHealthCheckConfig,
+  TServiceState,
+  TServiceCriticality,
+  TServiceEventType,
+  TOverallHealth,
+} from './taskbuffer.interfaces.js';
+
 import * as distributedCoordination from './taskbuffer.classes.distributedcoordinator.js';
 export { distributedCoordination };