[express]: how to put a sidebar in a `navset_card_tab()` context manager?

With Shiny Core, you can create an app with this layout using the following code:

from shiny import App, ui

ui = ui.page_fluid(ui.navset_card_tab(
    ui.nav_panel("A", "Panel A content"),
    ui.nav_panel("B", "Panel B content"),
    title="Card with navbar",
    sidebar=ui.sidebar(
        ui.input_select("data", "Data", ("A", "B", "C"))
    ),
))

def server(input):
    pass

app = App(ui, server)

But when I try it in shiny.express using the following code it doesn't work

from shiny.express import ui
ui.page_opts(fillable=True)

with ui.navset_card_tab(title="Card with navbar"):  
    with ui.sidebar():
        ui.input_select("data", "Data", ("A", "B", "C"))
    with ui.nav_panel("A"):
        "Panel A content"
    with ui.nav_panel("B"):
        "Panel B content"

Start by reproducing the shiny.express snippet and comparing it with the working Shiny Core example in the issue. Trace how navset_card_tab, sidebar, and nav_panel are composed in the Express context-manager form. Done means the Express form supports the same sidebar layout as the Core example.