feat(KB-648): enable parallel test execution and optimize test performance

- Optimize backup tests using fake timers instead of real timeouts

- Enable parallel file execution in core, engine, CLI, and dashboard packages

- Add inline test helpers to reduce dependencies in dashboard routes tests

- Update executor tests with exact command matching and improved assertions

- Update AGENTS.md with test optimization patterns (fake timers, unique temp dirs)

packages/dashboard/app/components/__tests__/NewTaskModal.test.tsx

@@ -128,7 +128,7 @@ describe("NewTaskModal", () => {
     fireEvent.click(screen.getByRole("button", { name: "Create Task" }));
     
     await waitFor(() => {
-      expect(props.addToast).toHaveBeenCalledWith("Created FN-042", "success");
+      expect(props.addToast).toHaveBeenCalledWith("Created KB-042", "success");
     });
   });