Onboarding: prompt permissions in context + data page

Location and network fetches no longer fire at launch before onboarding
reaches the relevant step: foreground tracking and the first refresh are
gated behind onboarding completion (scenePhase no longer starts tracking
while the cover is up, and onAppear defers its fetch until after
finish). A new Data page sits just before 'You're all set': it probes
the FuelBoard Relay, which surfaces the iOS Local Network permission
prompt in context (NSLocalNetworkUsageDescription added), verifies
connectivity, and offers Open Settings/Check again on denial. Onboarding
is now 5 pages: Welcome, Location, Notifications, Data, Done. 35 tests
pass.

FuelBoard/ContentView.swift

@@ -165,28 +165,40 @@ struct ContentView: View {
         }
         .onAppear {
             // Onboarding runs first on a fresh install — it owns the initial
-            // permission prompts. Location tracking starts once it's done.
+            // permission prompts (location, notifications, and the data/local
+            // network probe on the Data page). Location tracking and the first
+            // network fetch start once it's done.
             if FuelStore.loadHasCompletedOnboarding() {
                 locationManager.startForegroundTracking()
+                monitor.update(stations: stations, favourites: refreshedFavourites,
+                               fuel: alertsFuel, radiusKM: alertsRadius)
+                monitor.setEnabled(alertsEnabled)
+                // Refresh only when the cache is stale (twice-a-day policy).
+                Task { await refresh() }
             } else {
                 showOnboarding = true
             }
-            monitor.update(stations: stations, favourites: refreshedFavourites,
-                           fuel: alertsFuel, radiusKM: alertsRadius)
-            monitor.setEnabled(alertsEnabled)
-            // Refresh only when the cache is stale (twice-a-day policy).
-            Task { await refresh() }
         }
         .onChange(of: showOnboarding) { _, showing in
             // After onboarding finishes (or the test re-run is dismissed),
-            // begin foreground location tracking if permission allows.
+            // begin foreground location tracking if permission allows, and
+            // run the first data fetch (the relay probe during onboarding
+            // already surfaced the Local Network prompt).
             if !showing, FuelStore.loadHasCompletedOnboarding() {
                 locationManager.startForegroundTracking()
+                monitor.update(stations: stations, favourites: refreshedFavourites,
+                               fuel: alertsFuel, radiusKM: alertsRadius)
+                Task { await refresh() }
             }
         }
         .onChange(of: scenePhase) { _, newPhase in
             if newPhase == .active {
-                locationManager.startForegroundTracking()
+                // Never start location tracking while onboarding is on screen —
+                // onboarding owns the initial permission prompts. Once it's
+                // completed, normal foreground tracking resumes.
+                if !showOnboarding, FuelStore.loadHasCompletedOnboarding() {
+                    locationManager.startForegroundTracking()
+                }
                 monitor.update(stations: stations, favourites: refreshedFavourites,
                                fuel: alertsFuel, radiusKM: alertsRadius)
                 // No network fetch on foreground — pull-to-refresh is the override.