feat: restore the alert feed homepage widget

plugins/alerts/tests/frontend/activate.test.tsx

@@ -148,3 +148,50 @@ describe("the alerts panel", () => {
     );
   });
 });
+
+describe("the alert feed homepage widget", () => {
+  it("registers under the 2.8 widget id", async () => {
+    rendered = await renderWithApp(plugin, { manifest, locales });
+    expect(rendered.registered.extensions("homepage.widgets")).toEqual([
+      "alert_feed",
+    ]);
+  });
+
+  it("shows unread alerts and marks one read", async () => {
+    const { api, calls } = stubApi();
+    rendered = await renderWithApp(plugin, { manifest, locales, api });
+    const view = rendered.renderExtension(
+      "homepage.widgets",
+      "alert_feed",
+      "view",
+      {
+        widget: { title: null },
+        config: { maxItems: 5, showRead: false },
+      },
+    );
+    await waitFor(() =>
+      expect(view.textContent).toContain("Certificate renewal failed"),
+    );
+    expect(calls).toContainEqual(["GET", "/items?unread=true&limit=5"]);
+    fireEvent.click(view.querySelector('[title="Mark as read"]')!);
+    await waitFor(() =>
+      expect(calls).toContainEqual([
+        "POST",
+        "/items/read",
+        { ids: [2], read: true },
+      ]),
+    );
+  });
+
+  it("reads the 2.8 showAcknowledged option", async () => {
+    const { api, calls } = stubApi();
+    rendered = await renderWithApp(plugin, { manifest, locales, api });
+    rendered.renderExtension("homepage.widgets", "alert_feed", "view", {
+      widget: {},
+      config: { maxItems: 3, showAcknowledged: true },
+    });
+    await waitFor(() =>
+      expect(calls).toContainEqual(["GET", "/items?limit=3"]),
+    );
+  });
+});