Live Activity: own fuel + distance config, independent of Stations tab

- Settings → Live Activity now has Fuel and Distance pickers (5/10/15,
  unit-aware) stored under fuelboard.liveActivityFuel / liveActivityRadiusMiles
- LiveActivityManager uses these instead of the Stations-tab selectedFuel /
  stationLimit; Stations changes no longer re-target the pill
- Fuel moved from Activity attributes into ContentState so changing fuel in
  Settings updates the RUNNING activity in place (no end+restart needed)
- Stations tab stays a pure data-interrogation + favourites surface

FuelBoard/SettingsView.swift

@@ -13,9 +13,13 @@ import WidgetKit
 struct SettingsView: View {
     @Binding var distanceUnit: DistanceUnit
     /// Whether the "cheapest nearby" Live Activity is shown on the Lock Screen
-    /// / Dynamic Island. Mirrors the app list's TOP badge (selected fuel +
-    /// distance radius) and re-updates as the user drives.
+    /// / Dynamic Island. Tracks its OWN fuel + radius (below) — independent of
+    /// the Stations tab.
     @Binding var liveActivityEnabled: Bool
+    /// Fuel the Live Activity tracks (independent of the Stations tab).
+    @Binding var liveActivityFuel: FuelType
+    /// Search radius (miles, 5/10/15) the Live Activity uses.
+    @Binding var liveActivityRadiusMiles: Int
     /// The fuel + radius currently configured for alerts (mirrors the Alerts
     /// tab) so the test notification matches what real alerts will say.
     var alertsFuel: FuelType = .e10
@@ -72,10 +76,26 @@ struct SettingsView: View {
 
                 Section {
                     Toggle("Live Activity", isOn: $liveActivityEnabled)
+                    Picker("Fuel", selection: $liveActivityFuel) {
+                        ForEach(FuelType.allCases) { fuel in
+                            Text(fuel.displayName).tag(fuel)
+                        }
+                    }
+                    .onChange(of: liveActivityFuel) { _, newValue in
+                        FuelStore.saveLiveActivityFuel(newValue)
+                    }
+                    Picker("Distance", selection: $liveActivityRadiusMiles) {
+                        ForEach(FuelStore.stationRadiusOptions, id: \.self) { miles in
+                            Text("\(miles) \(distanceUnit.label)").tag(miles)
+                        }
+                    }
+                    .onChange(of: liveActivityRadiusMiles) { _, newValue in
+                        FuelStore.saveLiveActivityRadiusMiles(newValue)
+                    }
                 } header: {
                     Text("Live Activity")
                 } footer: {
-                    Text("Shows the cheapest station for your selected fuel within your chosen distance on the Lock Screen and Dynamic Island. Updates as you drive; tap to open directions. Live Activities can be disabled in System Settings → Live Activities.")
+                    Text("Shows the cheapest station for the fuel and distance you pick here on the Lock Screen and Dynamic Island — independent of the Stations tab. Updates as you drive; tap to open directions. Live Activities can be disabled in System Settings → Live Activities.")
                 }
                 .onChange(of: liveActivityEnabled) { _, newValue in
                     FuelStore.saveLiveActivityEnabled(newValue)