fix(app): update route test expectations for b64_ workspace ID prefix

The opaque-workspace-identifier refactor (e6044264) added a `b64_` prefix
to base64-encoded workspace IDs in route builders. Two app tests still
expected the unprefixed form and failed in CI.

packages/app/src/utils/new-agent-routing.test.ts

@@ -16,7 +16,7 @@ describe("buildNewAgentRoute", () => {
 
   it("encodes the working directory as a workspace path segment", () => {
     expect(buildNewAgentRoute("srv-1", "/Users/me/dev/paseo")).toBe(
-      "/h/srv-1/workspace/L1VzZXJzL21lL2Rldi9wYXNlbw",
+      "/h/srv-1/workspace/b64_L1VzZXJzL21lL2Rldi9wYXNlbw",
     );
   });
 });