Real iPhone wallpaper + populated Favourites captures

- PreviewWallpaper image set: the actual iPhone wallpaper extracted from the
  iOS 26.3 sim runtime (ActionButtonSelector Display.ca, 1320x2870 native
  res, JPEG ~180 KB) — replaces the gradient backdrop in the widget mock
- -seedFavourite <substring> launch hook: pins the first matching station
  for Unleaded via the normal keychain+app-group save path, so the
  Favourites tab can be captured populated (Ring Road Service Station,
  129.9, 59.1 mi, TOP badge)
- Re-captured 2-favourites (light), 6-favourites-dark, 9-widgets-dark,
  10-widgets-light with real data
- 95/95 tests green; Release IPA rebuilt + re-served

FuelBoard/ContentView.swift

@@ -186,6 +186,16 @@ struct ContentView: View {
             // without touching the stored flag.
             let args = ProcessInfo.processInfo.arguments
             showWidgetMock = args.contains("-widgets")
+            // `-seedFavourite <substring>` pins the first matching station
+            // for Unleaded via the normal save path (keychain + app group)
+            // so screenshot captures can show a populated Favourites tab.
+            if let i = args.firstIndex(of: "-seedFavourite"), i + 1 < args.count {
+                let query = args[i + 1]
+                if let station = FuelStore.loadStations()
+                    .first(where: { $0.name.localizedCaseInsensitiveContains(query) }) {
+                    FuelStore.saveFavourites([FavouriteEntry(station: station, fuel: .e10)])
+                }
+            }
             if let i = args.firstIndex(of: "-tab"), i + 1 < args.count {
                 switch args[i + 1] {
                 case "favourites": selectedTab = 1