Fix small widget skeleton: use the proven medium intent; delete failing small intent

ROOT CAUSE (proven by A/B test on-device): the small widget's custom
intent (FuelBoardSmallWidgetConfigurationIntent with favouriteFuel +
favourite AppEntity params) fails fresh-widget default-config resolution
at the system level — the whole default config fails, no timeline is
ever requested, makeEntry never runs, widget stays on the skeleton.
A minimal small widget sharing the MEDIUM intent (fuel/sort/distance
only) populated immediately in the same extension on the same device.
Neither removing defaultResult() (4d35b08) nor the
@IntentParameterDependency (8a9e775) helped — the extra entity params
themselves break resolution.

FIX: FuelPriceSmallWidget now uses FuelBoardWidgetConfigurationIntent
exactly like the working test widget. FuelBoardSmallWidgetConfiguration
Intent, FavouriteFuel(+Query), WidgetFavourite(+Query) deleted; the
pinned-favourite picker is gone (approved tradeoff). Favourites sort
still works on both faces via the list branch — the small face renders
the cheapest favourite of the chosen fuel. Beacon tag distinguishes the
small widget in diagnostics; test widget removed, gallery order
restored (small, medium, live activity).

FuelBoardWidgets/FuelBoardWidgetsBundle.swift

@@ -4,10 +4,7 @@ import SwiftUI
 @main
 struct FuelBoardWidgetsBundle: WidgetBundle {
     var body: some Widget {
-        // Gallery order follows registration order. The A/B test widget is
-        // first so it's easy to find; remove it once the small-widget root
-        // cause is confirmed.
-        FuelBoardTestSmallWidget()
+        // Gallery order follows registration order: small first, then medium.
         FuelPriceSmallWidget()
         FuelPriceWidget()
         FuelBoardLiveActivity()