fix(lifecycle): use process group kill (-pid) in handleExit safety net

With detached:true children, the synchronous exit handler must kill
the entire process group, not just the direct PID.

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@push.rocks/smartexit",
-  "version": "2.0.1",
+  "version": "2.0.2",
   "private": false,
   "description": "A library for managing graceful shutdowns of Node.js processes by handling cleanup operations, including terminating child processes.",
   "main": "dist_ts/index.js",

ts/smartexit.classes.lifecycle.ts

@@ -187,13 +187,19 @@ export class ProcessLifecycle {
     });
   }
 
-  /** Synchronous last-resort: SIGKILL any remaining tracked PIDs. */
+  /** Synchronous last-resort: SIGKILL any remaining tracked process groups. */
   private handleExit(): void {
     const instances = ProcessLifecycle.getInstances();
     let killed = 0;
 
     for (const instance of instances) {
       for (const pid of instance.trackedPids) {
+        // Kill entire process group (negative PID) for detached children
+        try {
+          process.kill(-pid, 'SIGKILL');
+          killed++;
+        } catch {
+          // Process group may not exist, try single PID
           try {
             process.kill(pid, 'SIGKILL');
             killed++;
@@ -202,6 +208,7 @@ export class ProcessLifecycle {
           }
         }
       }
+    }
 
     if (killed > 0 && !this.options.silent) {
       console.error(`[smartexit] Exit handler: force-killed ${killed} remaining child processes`);