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/session.ts

@@ -1,5 +1,6 @@
 import type { SessionManager } from "@/session-manager/manager";
 import type { RpcError } from "@/transport/types";
+import { clearRecordingForSession } from "./record";
 import { returnBorrowedTab, type TabManagementDeps } from "./tabs";
 
 export interface SessionStartParams {
@@ -156,6 +157,8 @@ export async function handleSessionStop(
   // Step 2: clear the per-session RefStore (review M6/M7 parity).
   ctx.refStore.clear();
 
+  clearRecordingForSession(params.session_id);
+
   // Step 3: detach CDP sessions this session opened (no-op if none).
   await deps.cdp?.detachSession(params.session_id);