fix(beszel): prevent live subscription memory growth (#6448)

* fix(beszel): bound live stats subscriptions

* fix(beszel): avoid blocking subscription teardown

* fix(import): map new clock options

packages/api/src/router/widgets/__tests__/bounded-async-queue.spec.ts

@@ -0,0 +1,45 @@
+import { describe, expect, test } from "vitest";
+
+import { BoundedAsyncQueue } from "../bounded-async-queue";
+
+describe("BoundedAsyncQueue", () => {
+  test("keeps only the newest values when the queue is full", async () => {
+    const queue = new BoundedAsyncQueue<number>(2);
+    queue.push(1);
+    queue.push(2);
+    queue.push(3);
+    queue.close();
+
+    await expect(queue.next()).resolves.toEqual({ value: 2, done: false });
+    await expect(queue.next()).resolves.toEqual({ value: 3, done: false });
+    await expect(queue.next()).resolves.toEqual({ value: undefined, done: true });
+  });
+
+  test("resolves a pending read as soon as a value arrives", async () => {
+    const queue = new BoundedAsyncQueue<string>(1);
+    const next = queue.next();
+
+    queue.push("latest");
+
+    await expect(next).resolves.toEqual({ value: "latest", done: false });
+  });
+
+  test("resolves a pending read when the producer closes", async () => {
+    const queue = new BoundedAsyncQueue<number>(1);
+    const next = queue.next();
+
+    queue.close();
+
+    await expect(next).resolves.toEqual({ value: undefined, done: true });
+  });
+
+  test("rejects a pending read when the producer fails", async () => {
+    const queue = new BoundedAsyncQueue<number>(1);
+    const next = queue.next();
+    const error = new Error("upstream failed");
+
+    queue.fail(error);
+
+    await expect(next).rejects.toBe(error);
+  });
+});