Fix widget distance menu + geofence notification chain

Widget distance menu: the Distance picker only makes sense for
Cheapest ordering. It was hidden for Favourites but Closest still
showed it (regressed when the per-widget Distance picker was added).
parameterSummary now nests When clauses: Distance visible for
Cheapest only; Closest and Favourites hide it.

Notifications: three compounding defects kept real geofence alerts
from ever firing while the app was suspended:

1. Always permission was never properly requested. requestPermissions
   fired WhenInUse and Always back-to-back; iOS ignores the second
   call while the first prompt is pending, leaving the app stuck on
   WhenInUse — and region entries are never delivered in the
   background. Added locationManagerDidChangeAuthorization to
   ProximityMonitor: escalate WhenInUse -> Always, and re-register
   geofences on grant (regions registered under WhenInUse-only won't
   deliver in the background).

2. The 18-region window was frozen in the background. Re-registration
   lived in SwiftUI .onChange(of: locationManager.current), which
   never runs while suspended. Added a delegate hook
   (LocationManager.onLocationUpdate) fired from didUpdateLocations on
   every fix including background significant-change wake-ups; the app
   wires it to re-register geofences around the new position.

3. Region-registration failures were invisible. monitoringDidFailFor
   was never implemented, so a failed startMonitoring (region budget,
   auth, radius) silently stopped alerts. Now surfaced as
   monitor.lastRegionError and shown in Settings -> Debug; cleared on
   the next successful registration.

FuelBoardWidgets/WidgetConfigIntent.swift

@@ -70,20 +70,28 @@ struct FuelBoardWidgetConfigurationIntent: WidgetConfigurationIntent {
     @Parameter(title: "Distance", default: .five)
     var distance: WidgetDistance
 
-    /// Edit-Widget UI: Favourites ranks pinned stations cheapest-first and is
-    /// not radius-bound, so the Distance picker is hidden in that mode.
+    /// Edit-Widget UI: the Distance picker only makes sense for Cheapest
+    /// ordering — Closest is inherently "nearest within range" and Favourites
+    /// is not radius-bound. Show it for Cheapest only; hide for both others.
     static var parameterSummary: some ParameterSummary {
-        When(\.$sort, .equalTo, WidgetSort.favourites) {
-            Summary("Show \(\.$fuel) favourites") {
-                \.$fuel
-                \.$sort
-            }
-        } otherwise: {
+        When(\.$sort, .equalTo, WidgetSort.cheapest) {
             Summary("Show \(\.$fuel) by \(\.$sort) within \(\.$distance)") {
                 \.$fuel
                 \.$sort
                 \.$distance
             }
+        } otherwise: {
+            When(\.$sort, .equalTo, WidgetSort.favourites) {
+                Summary("Show \(\.$fuel) favourites") {
+                    \.$fuel
+                    \.$sort
+                }
+            } otherwise: {
+                Summary("Show \(\.$fuel) by \(\.$sort)") {
+                    \.$fuel
+                    \.$sort
+                }
+            }
         }
     }
 }