Widget opens Maps via maps://; onboarding prompts after Continue; forced first fetch

- Widget tap-to-directions now uses the native maps:// scheme instead of
  http://maps.apple.com. The universal-link http URL failed to open from a
  widget and fell back to launching the containing app; maps:// opens
  Apple Maps directly for both small (whole widget) and medium (per row).
- Onboarding: removed the Skip button (mandatory flow), and system prompts
  (location, notifications, local network) now fire only when the user taps
  Continue/Allow on each page — not when the page appears. Pages
  auto-advance once a permission is granted.
- After 'Start Using FuelBoard' the first data fetch is forced, so a
  reinstall that leaves a recent lastRefresh in app-group defaults can no
  longer skip the fetch and leave the station list empty. 35 tests pass.

FuelBoard/ContentView.swift

@@ -182,13 +182,16 @@ struct ContentView: View {
         .onChange(of: showOnboarding) { _, showing in
             // After onboarding finishes (or the test re-run is dismissed),
             // begin foreground location tracking if permission allows, and
-            // run the first data fetch (the relay probe during onboarding
-            // already surfaced the Local Network prompt).
+            // run the FIRST data fetch. This must be a forced refresh: a
+            // reinstall may leave a recent `lastRefresh` in the app-group
+            // defaults (which survive app deletion), which would make the
+            // cache-gated refresh skip the fetch and leave the station list
+            // empty on a brand-new install.
             if !showing, FuelStore.loadHasCompletedOnboarding() {
                 locationManager.startForegroundTracking()
                 monitor.update(stations: stations, favourites: refreshedFavourites,
                                fuel: alertsFuel, radiusKM: alertsRadius)
-                Task { await refresh() }
+                Task { await refresh(force: true) }
             }
         }
         .onChange(of: scenePhase) { _, newPhase in