Live-test fixes: CarPlay disfavor, widget location refresh, debug cheapest parity

1. CarPlay widget taps could never launch Maps — FuelBoard is not a
   CarPlay app, and Apple only lets a widget launch its own app in
   CarPlay when that app is CarPlay-enabled. Marked the widget as a
   disfavored CarPlay location (iOS 26+; no-op below): read-only in
   the car, no dead tap. Header comment updated to match reality.

2. Widgets now track the user's location: timeline refresh 15m -> 5m,
   and the app's location manager reloads all widget timelines after
   every significant move (250m filter, throttled to 60s), so the
   widget re-orders around the new position while driving instead of
   waiting for the next tick.

3. Debug 'Cheapest in range' no longer shows the ALERT prediction
   (alertsFuel + alert radius — a different pool by design). It now
   mirrors the app list exactly: the TOP-badge station for the
   selected fuel within the stationLimit radius (new DebugAppCheapest
   computed in ContentView, passed to Settings). Alert-prediction
   cheapest kept as fallback when the app view hasn't resolved.

FuelBoardWidgets/FuelPriceWidget.swift

@@ -5,13 +5,18 @@ 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=). 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).
+// Taps deep-link to Apple Maps directions (maps://?daddr=). 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).
+//
+// CarPlay: this widget is marked as a DISFAVORED location there. Widgets in
+// CarPlay can only launch their OWN app, and only when that app is itself a
+// CarPlay app (fueling entitlement). FuelBoard is not a CarPlay app, so a
+// tap in the car would be a dead interaction — Apple's guidance for widgets
+// whose purpose is launching a non-CarPlay app is to disfavor CarPlay: the
+// widget stays visible (read-only prices) but interaction is disabled, so
+// there is no tap that silently does nothing.
 //
 // Each widget instance is configured INDEPENDENTLY via its own App Intent
 // (long-press → Edit Widget): fuel type (Unleaded/Premium/Diesel) and sort
@@ -30,6 +35,24 @@ struct FuelPriceWidget: Widget {
     let kind = "FuelPriceWidget"
 
     var body: some WidgetConfiguration {
+        // 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.
+        baseConfiguration()
+            .disfavoredLocations(carPlayLocations, for: [.systemSmall])
+    }
+
+    private var carPlayLocations: [WidgetLocation] {
+        if #available(iOS 26.0, *) {
+            return [.carPlay]
+        }
+        return []
+    }
+
+    private func baseConfiguration() -> some WidgetConfiguration {
         AppIntentConfiguration(
             kind: kind,
             intent: FuelBoardWidgetConfigurationIntent.self,
@@ -79,7 +102,9 @@ struct FuelPriceTimelineProvider: AppIntentTimelineProvider {
         in context: Context
     ) async -> Timeline<FuelPriceEntry> {
         let entry = await makeEntry(configuration: configuration)
-        let nextRefresh = Calendar.current.date(byAdding: .minute, value: 15, to: Date())!
+        // Short cadence so the widget re-orders around a new location while
+        // driving — the provider re-fetches a fresh fix + prices each tick.
+        let nextRefresh = Calendar.current.date(byAdding: .minute, value: 5, to: Date())!
         return Timeline(entries: [entry], policy: .after(nextRefresh))
     }