Add web front-end and fix API issues

node_modules/concurrently/dist/lib/observables.d.ts

@@ -0,0 +1,8 @@
+import EventEmitter from 'node:events';
+import { Observable } from 'rxjs';
+/**
+ * Creates an observable for a specific event of an `EventEmitter` instance.
+ *
+ * The underlying event listener is set up only once across the application for that event emitter/name pair.
+ */
+export declare function fromSharedEvent(emitter: EventEmitter, event: string): Observable<unknown>;