feat: add bsk record for semantic user-action traces

Capture user actions in the Agent Window and export a record-only
trace (pages[] + navigate/click/fill/select/press steps with target
descriptors). Adds the record overlay UI aligned with the control
overlay, and wires record start/stop/await through CLI, daemon,
protocol, and extension.

apps/extension/src/tools/__tests__/record-observation.test.ts

@@ -0,0 +1,52 @@
+import { afterEach, describe, expect, it, vi } from "vitest";
+import {
+  ensureBrowserObservationListeners,
+  isBrowserObservationAttachedForTests,
+  releaseBrowserObservationListenersIfIdle,
+  resetBrowserObservationForTests,
+  setBrowserObservationAttachForTests,
+} from "../record";
+
+describe("browser observation lifecycle", () => {
+  afterEach(() => {
+    resetBrowserObservationForTests();
+  });
+
+  it("does not attach listeners until ensure is called", () => {
+    const tab = vi.fn(() => () => undefined);
+    const nav = vi.fn(() => () => undefined);
+    setBrowserObservationAttachForTests(tab, nav);
+
+    expect(isBrowserObservationAttachedForTests()).toBe(false);
+    expect(tab).not.toHaveBeenCalled();
+    expect(nav).not.toHaveBeenCalled();
+  });
+
+  it("attaches once on ensure and detaches when idle", () => {
+    const detachTab = vi.fn();
+    const detachNav = vi.fn();
+    const tab = vi.fn(() => detachTab);
+    const nav = vi.fn(() => detachNav);
+    setBrowserObservationAttachForTests(tab, nav);
+
+    ensureBrowserObservationListeners({
+      tabsApi: { get: vi.fn(), query: vi.fn(), create: vi.fn() } as never,
+      sendToTab: vi.fn(),
+    });
+    expect(isBrowserObservationAttachedForTests()).toBe(true);
+    expect(tab).toHaveBeenCalledTimes(1);
+    expect(nav).toHaveBeenCalledTimes(1);
+
+    // Idempotent.
+    ensureBrowserObservationListeners({
+      tabsApi: { get: vi.fn(), query: vi.fn(), create: vi.fn() } as never,
+      sendToTab: vi.fn(),
+    });
+    expect(tab).toHaveBeenCalledTimes(1);
+
+    releaseBrowserObservationListenersIfIdle();
+    expect(isBrowserObservationAttachedForTests()).toBe(false);
+    expect(detachTab).toHaveBeenCalledTimes(1);
+    expect(detachNav).toHaveBeenCalledTimes(1);
+  });
+});