Deliver alert immediately; map attaches in place afterwards

The notification used to be added only inside the MKMapSnapshotter
completion — if the snapshot hung or failed, no notification was ever
delivered and the result line never showed the map status. Now the
notification fires immediately (same identifier), the snapshot renders
in the background with an 8s timeout, and on success the delivered
notification is replaced in place with the map attached. Result line
always updates: preparing -> attached / failed / timed out.

FuelBoard/ProximityMonitor.swift

@@ -207,6 +207,16 @@ final class ProximityMonitor: NSObject, ObservableObject, @preconcurrency CLLoca
             "stationLat": station.lat,
             "stationLng": station.lng,
         ]
+        let identifier = UUID().uuidString
+
+        // Deliver the notification IMMEDIATELY — the alert must never wait on
+        // the map. If the snapshot later succeeds, the same identifier is used
+        // to replace the delivered notification with the map attached.
+        mapStatus?("map: preparing…")
+        UNUserNotificationCenter.current().add(
+            UNNotificationRequest(identifier: identifier, content: content, trigger: nil)
+        )
+
         let options = MKMapSnapshotter.Options()
         options.region = MKCoordinateRegion(
             center: CLLocationCoordinate2D(latitude: station.lat, longitude: station.lng),
@@ -215,8 +225,24 @@ final class ProximityMonitor: NSObject, ObservableObject, @preconcurrency CLLoca
         options.size = CGSize(width: 800, height: 400)
         options.mapType = .standard
         let snapshotter = MKMapSnapshotter(options: options)
-        snapshotter.start { [content] snapshot, error in
+
+        // Timeout so a hung snapshot can't leave the result line stuck on
+        // "preparing" forever.
+        var finished = false
+        let timeout = DispatchWorkItem {
             Task { @MainActor in
+                guard !finished else { return }
+                finished = true
+                mapStatus?("map: timed out")
+            }
+        }
+        DispatchQueue.main.asyncAfter(deadline: .now() + 8, execute: timeout)
+
+        snapshotter.start { [content] snapshot, error in
+            timeout.cancel()
+            Task { @MainActor in
+                guard !finished else { return }
+                finished = true
                 let finalContent = content
                 var status = "map: no image"
                 if let snapshot, error == nil,
@@ -232,8 +258,11 @@ final class ProximityMonitor: NSObject, ObservableObject, @preconcurrency CLLoca
                     status = "map: snapshot failed (\(error.localizedDescription))"
                 }
                 mapStatus?(status)
-                let request = UNNotificationRequest(identifier: UUID().uuidString, content: finalContent, trigger: nil)
-                UNUserNotificationCenter.current().add(request)
+                // Replace the delivered notification (same identifier) so the
+                // map appears in place.
+                UNUserNotificationCenter.current().add(
+                    UNNotificationRequest(identifier: identifier, content: finalContent, trigger: nil)
+                )
             }
         }
     }
@@ -282,10 +311,10 @@ final class ProximityMonitor: NSObject, ObservableObject, @preconcurrency CLLoca
             content.body = "\(candidate.name) · \(distanceText) away · \(String(format: "%.1fp", price)). Tap for directions."
             content.sound = .default
             let baseResult = "\(fuel.displayName) · \(brand) · \(String(format: "%.1fp", price)) · \(distanceText) away · radius \(unit.format(radiusKM))"
+            lastTestResult = baseResult
             addAlertRequest(content: content, station: candidate) { status in
                 self.lastTestResult = "\(baseResult) · \(status)"
             }
-            lastTestResult = baseResult
         } else {
             // No real candidate (no stations loaded yet, or none sell the
             // monitored fuel) — still fire so delivery is testable, but say