Raise deployment target to iOS 26.0; enable CarPlay Live Activity

- IPHONEOS_DEPLOYMENT_TARGET 17.0 -> 26.0 (iPhone 11+, Apple's current floor)
- Widget CarPlay disfavor is now unconditional (no #available guard)
- Live Activity gains supplementalActivityFamilies([.small]) so it renders
  in the car's small slot on CarPlay Ultra (display-only: FuelBoard has no
  CarPlay entitlement, car taps can't launch anything)

FuelBoardWidgets/FuelPriceWidget.swift

@@ -38,18 +38,9 @@ struct FuelPriceWidget: Widget {
         // CarPlay: mark as disfavored — FuelBoard is not a CarPlay app, so
         // widget taps there can never launch Maps (Apple only allows a widget
         // to launch its own app in CarPlay, and only CarPlay-enabled apps).
-        // Disfavored = read-only in the car, no dead interaction. The
-        // locations array is empty below iOS 26 where `.carPlay` doesn't
-        // exist, making the modifier a harmless no-op there.
+        // Disfavored = read-only in the car, no dead interaction.
         baseConfiguration()
-            .disfavoredLocations(carPlayLocations, for: [.systemSmall])
-    }
-
-    private var carPlayLocations: [WidgetLocation] {
-        if #available(iOS 26.0, *) {
-            return [.carPlay]
-        }
-        return []
+            .disfavoredLocations([.carPlay], for: [.systemSmall])
     }
 
     private func baseConfiguration() -> some WidgetConfiguration {