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

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@push.rocks/taskbuffer",
-  "version": "6.1.2",
+  "version": "7.0.0",
   "private": false,
   "description": "A flexible task management library supporting TypeScript, allowing for task buffering, scheduling, and execution with dependency management.",
   "main": "dist_ts/index.js",