Add web front-end and fix API issues

node_modules/concurrently/dist/lib/output-writer.d.ts

@@ -0,0 +1,22 @@
+import { Writable } from 'node:stream';
+import Rx from 'rxjs';
+import { Command } from './command.js';
+/**
+ * Class responsible for actually writing output onto a writable stream.
+ */
+export declare class OutputWriter {
+    private readonly outputStream;
+    private readonly group;
+    readonly buffers: string[][];
+    activeCommandIndex: number;
+    readonly error: Rx.Observable<unknown>;
+    private get errored();
+    constructor({ outputStream, group, commands, }: {
+        outputStream: Writable;
+        group: boolean;
+        commands: Command[];
+    });
+    private ensureWritable;
+    write(command: Command | undefined, text: string): void;
+    private flushBuffer;
+}