feat(web): add Agent Studio workspace UI

apps/web/tests/states.test.tsx

@@ -0,0 +1,17 @@
+import { render, screen } from "@testing-library/react";
+import "@testing-library/jest-dom/vitest";
+import { describe, expect, it } from "vitest";
+import { StateView } from "../src/components/common/StateView.js";
+
+describe("StateView", () => {
+  it.each([
+    ["loading", "正在建立训练会话"],
+    ["reconnecting", "事件流正在重连"],
+    ["busy", "Agent 正在运行"],
+    ["approval", "等待工具审批"],
+    ["error", "会话启动失败"],
+  ] as const)("renders the %s state", (kind, label) => {
+    render(<StateView kind={kind} title={label} />);
+    expect(screen.getByText(label)).toBeVisible();
+  });
+});