feat: add widgets preview component

Co-authored-by: sawka <2722291+sawka@users.noreply.github.com>

Author: Copilot

frontend/app/workspace/widgets.test.ts

@@ -0,0 +1,17 @@
+// Copyright 2026, Command Line Inc.
+// SPDX-License-Identifier: Apache-2.0
+
+import { assert, test } from "vitest";
+import { getWidgetsMode } from "./widgets";
+
+test("getWidgetsMode returns normal when the measured content fits", () => {
+    assert.equal(getWidgetsMode(240, 225, 6), "normal");
+});
+
+test("getWidgetsMode returns compact when normal content overflows but compact height still fits", () => {
+    assert.equal(getWidgetsMode(240, 260, 6), "compact");
+});
+
+test("getWidgetsMode returns supercompact when even the compact layout would overflow", () => {
+    assert.equal(getWidgetsMode(120, 260, 6), "supercompact");
+});