feat: add Python and Java regex engines

src/regex/execution/WorkerSupervisor.ts

@@ -58,6 +58,10 @@ export class WorkerSupervisor<TOperation, TResult> {
     return this.active !== null;
   }
 
+  get hasWorker(): boolean {
+    return this.worker !== null;
+  }
+
   run(
     operation: TOperation,
     timeoutMs: number,