feat: station tap action toggle (open map vs more info)

Settings → Units gains a Tap station picker: Open map (default,
historic behaviour — tap opens Apple Maps directions) or More info
(tap shows a detail sheet with name, address, distance from current
location, and a Directions button). Applies to Stations and
Favourites tabs; persisted keychain-first as
fuelboard.stationTapAction. Stations footer hint follows the setting.

FuelBoard/StationsView.swift

@@ -15,6 +15,7 @@ struct StationsView: View {
     let topStationID: String?
     let location: Coordinate?
     let favouriteIDs: Set<String>
+    let stationTapAction: StationTapAction
     var onToggleFavourite: (FuelStation, FuelType) -> Void = { _, _ in }
     var onRefresh: () async -> Void = {}
 
@@ -29,6 +30,9 @@ struct StationsView: View {
     /// info button in the header — keeps the list focused on stations.
     @State private var showKey = false
 
+    /// Station picked for the More-info sheet (tap action = showDetails).
+    @State private var detailStation: FuelStation?
+
     /// Bottom-of-tab explainer (moved from the top 2026-08-16): mode/radius/
     /// directions context + "N/TOTAL stations updated". The numerator is the
     /// current list pool; the denominator is the full UK station total from
@@ -38,6 +42,9 @@ struct StationsView: View {
         let unit = distanceUnit.label(for: Double(miles))
         let fuel = selectedFuel.displayName
         let mode = sortMode == .closest ? "Closest" : "Cheapest"
+        let tapHint = stationTapAction == .openMap
+            ? "tap a station for directions."
+            : "tap a station for details."
         let ratio: String
         if let total = FuelStore.loadStationCount() {
             ratio = "\(totalCount)/\(total)"
@@ -48,9 +55,9 @@ struct StationsView: View {
             if sortMode == .closest {
                 return "\(mode) \(fuel) stations — nearest first, best value within \(miles) \(unit) · \(ratio) stations updated"
             }
-            return "\(mode) \(fuel) within \(miles) \(unit) — \(ratio) stations updated · tap a station for directions."
+            return "\(mode) \(fuel) within \(miles) \(unit) — \(ratio) stations updated · \(tapHint)"
         }
-        return "\(mode) \(fuel) — \(ratio) stations updated · tap a station for directions."
+        return "\(mode) \(fuel) — \(ratio) stations updated · \(tapHint)"
     }
 
     var body: some View {
@@ -126,7 +133,9 @@ struct StationsView: View {
                                 baselinePrice: baselinePrice,
                                 isTopResult: station.id == topStationID,
                                 isFavourite: favouriteIDs.contains(station.id),
-                                onToggleFavourite: { onToggleFavourite(station, selectedFuel) }
+                                tapAction: stationTapAction,
+                                onToggleFavourite: { onToggleFavourite(station, selectedFuel) },
+                                onShowDetails: { detailStation = $0 }
                             )
                         }
 
@@ -260,6 +269,13 @@ struct StationsView: View {
                 .presentationDetents([.fraction(0.6)])
                 .presentationBackground(Color(UIColor.systemGroupedBackground))
             }
+            .sheet(item: $detailStation) { station in
+                StationDetailView(
+                    station: station,
+                    location: location,
+                    distanceUnit: distanceUnit
+                )
+            }
         }
     }