Refactor concurrency handling to introduce STALE_HEARTBEAT_THRESHOLD_MS constant and utilize SweepstoreWorkerTicketSnapshot for improved state management

dart/lib/sweepstore.dart

@@ -60,21 +60,25 @@ Future<void> main() async {
 
   Sweepstore store = Sweepstore(filePath);
   store.initialise(
-    concurrentWorkers: 18
+    concurrentWorkers: 32
   );
   initialiseMasterListener(file.openSync(mode: FileMode.append));
 
   print(binaryDump(file.readAsBytesSync()));
 
-  int iteration = 100;
+  int iteration = 0;
 
-  for (int j = 0; j < iteration; j++) {
+  print("Concurrent Workers: ${store._concurrencyHeader.numberOfWorkers}");
+  print("Stale Ticket Threshold: ${STALE_HEARTBEAT_THRESHOLD_MS}ms");
+
+  while (true) {
     int concurrencyTest = 128;
     final receivePort = ReceivePort();
     int completedJobs = 0;
 
     final stopwatch = Stopwatch()..start();
 
+    print('\x1B[95mStarting iteration #$iteration with $concurrencyTest concurrent jobs...\x1B[0m');
     for (int i = 0; i < concurrencyTest; i++) {
       await Isolate.spawn((message) {
         final index = message['index'] as int;
@@ -101,7 +105,9 @@ Future<void> main() async {
 
     print('\x1B[95mAll jobs completed!\x1B[0m');
     print('\x1B[95mTime taken: ${stopwatch.elapsedMilliseconds}ms (${stopwatch.elapsed.inSeconds}s)\x1B[0m');
+    print(" ");
 
     // sleep(Duration(seconds: 2));
+    iteration++;
   }
 }