Widget links maps:// directly so CarPlay can route to Apple Maps

- The widget now uses the native maps://?daddr= scheme for taps in both
  sizes. In CarPlay there is no containing app to relay through, but since
  Apple Maps IS a CarPlay app, the system may route the tap straight to
  Maps on the car display (WWDC25: widgets can launch apps in CarPlay).
- iOS keeps working via onOpenURL: the app now forwards maps:// URLs (if
  the Home Screen delivers them to the app), plus legacy fuelboard:// and
  http://maps.apple.com links from older cached timelines.
- No public API exists for a widget to detect CarPlay context, so the
  single maps:// link serves both; the app-side forward is the iOS safety
  net. 35 tests pass.

FuelBoardWidgets/FuelPriceWidget.swift

@@ -5,9 +5,13 @@ import AppIntents
 // FuelBoard widget — petrol stations near you.
 //   systemMedium: top 3-4 stations with price + distance, each row opens Maps
 //   systemSmall:  single station, whole widget opens Maps
-// Taps deep-link to Apple Maps directions (maps://?daddr=).
-// Note: on the home screen Link opens Maps directly. Inside CarPlay the widget
-// renders but can't launch Maps (widgets can only launch their own CarPlay app).
+// Taps deep-link to Apple Maps directions (maps://?daddr=). The widget uses
+// the native Maps scheme (not a custom app scheme) so that CarPlay can route
+// the tap straight to Apple Maps — which IS a CarPlay app — without needing
+// the containing app to launch. On the Home Screen the system either opens
+// Maps directly or delivers the URL to FuelBoard, whose onOpenURL forwards it
+// (and also still handles legacy fuelboard:// and http://maps.apple.com links
+// from older cached timelines).
 //
 // Each widget instance is configured INDEPENDENTLY via its own App Intent
 // (long-press → Edit Widget): fuel type (Unleaded/Premium/Diesel) and sort
@@ -261,7 +265,7 @@ struct FuelPriceWidgetView: View {
                     .foregroundStyle(.secondary)
             }
             ForEach(entry.stations.prefix(3)) { station in
-                Link(destination: station.widgetDirectionsURL ?? URL(string: "fuelboard://")!) {
+                Link(destination: station.widgetDirectionsURL ?? URL(string: "maps://")!) {
                     HStack(spacing: 8) {
                         Text(station.name)
                             .font(.caption.weight(.semibold))