Add concurrency handling implementation with ticket management and file locking

dart/lib/sweepstore.dart

@@ -72,10 +72,14 @@ Future<void> main() async {
   print("Stale Ticket Threshold: ${STALE_HEARTBEAT_THRESHOLD_MS}ms");
 
   while (true) {
-    int concurrencyTest = 128;
+    int concurrencyTest = 256;
     final receivePort = ReceivePort();
     int completedJobs = 0;
 
+    if (iteration > 0) {
+      break;
+    }
+
     final stopwatch = Stopwatch()..start();
 
     print('\x1B[95mStarting iteration #$iteration with $concurrencyTest concurrent jobs...\x1B[0m');