FuelPriceWidget now uses AppIntentConfiguration with a per-widget
FuelBoardWidgetConfigurationIntent (fuel + sort). Each widget placed on
the home screen carries its OWN fuel type (Unleaded/Premium/Diesel) and
ordering (Cheapest/Closest), edited by long-press -> Edit Widget —
independent of the app's selection, so multiple widgets can show
different data side by side. Widget no longer reads the app's selected
fuel. 35 tests pass.
