[tests] `ValueBox` controller assumes showcase is present

[gadenbuie]

py-shiny/tests/playwright/controls.py

Lines 2638 to 2642 in 446c8ac

	loc="> div > .value-box-grid",
	)
	value_box_grid = self.loc
	self.loc_showcase = value_box_grid.locator("> .value-box-showcase")
	self.loc_title = value_box_grid.locator("> .value-box-area > .value-box-title")

loc uses .value-box-grid, but this class may not be present if a plain value box without a showcase is used. It might be easier to use .bslib-value-box as the root selector.

Here's an example app where ValueBox().open_full_screen() will fail because loc_title can't be found.

from shiny.express import ui

with ui.value_box(id="my_value_box", full_screen=True):
    "Hello, value box!"
    "$1,234,567"