Settings Debug: device coordinates + in-range station indicator

- Debug section now shows the last device fix (lat/lng to 5dp) and its age.
- In-range indicator uses the SAME criteria as live alerts: stations selling
  the monitored fuel within the alert radius of the fix. Green dot + count
  when in range, red when none, grey while waiting for a fix.
- Shows the cheapest in-range station (name, distance, price).
- ProximityMonitor recomputes the snapshot on every location/stations
  change and on Debug-section appear; ContentView passes the live status.
- SettingsView extracted to its own property to keep TabView body within
  the compiler type-check budget. 35 tests pass.

FuelBoard/SettingsView.swift

@@ -24,7 +24,11 @@ struct SettingsView: View {
     /// Drives the plain test (no criteria) — routed to the live monitor so it
     /// can carry a real station's name, price and coordinates.
     var onPlainTestAlert: () -> Void = {}
+    /// Recomputes the debug location snapshot (coordinates + in-range count).
+    var onRefreshDebugStatus: () -> Void = {}
     var onShowOnboarding: () -> Void = {}
+    /// Live snapshot of the device fix + stations in range (from the monitor).
+    var debugStatus: DebugLocationStatus?
 
     @StateObject private var tipStore = TipStore()
     @State private var showTipAlert = false
@@ -88,11 +92,13 @@ struct SettingsView: View {
                         } label: {
                             Label("Send plain test notification", systemImage: "bell.slash.fill")
                         }
+                        debugLocationRows
                     } header: {
                         Text("Debug")
                     } footer: {
                         Text("The first button applies the real criteria — cheapest \(alertsFuel.displayName.lowercased()) station within \(distanceUnit.format(alertsRadiusKM)) of you — and sends the actual station's name, price and coordinates. The second fires with no criteria at all (nearest seller), still carrying a real station, just to verify a notification appears and tapping it opens directions.")
                     }
+                    .onAppear { onRefreshDebugStatus() }
                 }
 
                 Section {
@@ -146,6 +152,100 @@ struct SettingsView: View {
         }
     }
 
+    /// Debug location block: device coordinates + fix age, then the in-range
+    /// indicator. "In range" mirrors the live alert criteria — stations selling
+    /// the monitored fuel within the alert radius of the last fix.
+    @ViewBuilder
+    private var debugLocationRows: some View {
+        Divider()
+        if let status = debugStatus {
+            HStack {
+                Label("Device", systemImage: "location.fill")
+                Spacer()
+                if let coord = status.coordinate {
+                    Text(String(format: "%.5f, %.5f", coord.lat, coord.lng))
+                        .font(.footnote)
+                        .monospacedDigit()
+                        .foregroundStyle(.secondary)
+                } else {
+                    Text("No fix")
+                        .foregroundStyle(.secondary)
+                }
+            }
+            if let age = status.fixAge {
+                HStack {
+                    Label("Fix age", systemImage: "clock.fill")
+                    Spacer()
+                    Text(ageText(age))
+                        .font(.footnote)
+                        .foregroundStyle(.secondary)
+                }
+            }
+            HStack {
+                Label("In range", systemImage: "location.circle.fill")
+                Spacer()
+                HStack(spacing: 6) {
+                    if let coord = status.coordinate {
+                        Circle()
+                            .fill(inRangeColor(status.inRangeCount))
+                            .frame(width: 10, height: 10)
+                    } else {
+                        Circle()
+                            .fill(.gray)
+                            .frame(width: 10, height: 10)
+                    }
+                    Text(inRangeText(status))
+                        .font(.footnote)
+                        .foregroundStyle(.secondary)
+                }
+            }
+            if let cheapest = status.cheapestInRange {
+                HStack {
+                    Label("Cheapest in range", systemImage: "fuelpump.fill")
+                    Spacer()
+                    Text(cheapestText(cheapest, fuel: status.fuel, distance: status.cheapestDistanceKM))
+                        .font(.footnote)
+                        .monospacedDigit()
+                        .foregroundStyle(.secondary)
+                }
+            }
+        } else {
+            HStack {
+                Label("Device", systemImage: "location.fill")
+                Spacer()
+                Text("—")
+                    .foregroundStyle(.secondary)
+            }
+        }
+    }
+
+    private func inRangeColor(_ count: Int) -> Color {
+        count > 0 ? .green : .red
+    }
+
+    private func inRangeText(_ status: DebugLocationStatus) -> String {
+        guard status.coordinate != nil else { return "waiting for fix" }
+        let fuelName = status.fuel.displayName.lowercased()
+        if status.inRangeCount == 1 {
+            return "1 \(fuelName) station within \(distanceUnit.format(status.radiusKM))"
+        }
+        return "\(status.inRangeCount) \(fuelName) stations within \(distanceUnit.format(status.radiusKM))"
+    }
+
+    private func cheapestText(_ station: FuelStation, fuel: FuelType, distance: Double?) -> String {
+        let price = station.prices[fuel].map { String(format: "%.1fp", $0) } ?? "—"
+        if let distance {
+            return "\(station.name) · \(distanceUnit.format(distance)) · \(price)"
+        }
+        return "\(station.name) · \(price)"
+    }
+
+    private func ageText(_ age: TimeInterval) -> String {
+        if age < 60 { return "\(Int(age))s ago" }
+        if age < 3600 { return "\(Int(age / 60))m \(Int(age.truncatingRemainder(dividingBy: 60)))s ago" }
+        return "\(Int(age / 3600))h \(Int((age.truncatingRemainder(dividingBy: 3600)) / 60))m ago"
+    }
+
     private var appVersion: String {
         let version = Bundle.main.object(forInfoDictionaryKey: "CFBundleShortVersionString") as? String ?? "1.0"
         let build = Bundle.main.object(forInfoDictionaryKey: "CFBundleVersion") as? String ?? "1"