Widget shots: use the shipping app icon (light + dark variants)

- AppIconPreview now byte-identical to the real AppIcon.png (the preview
  had been pointing at an older Design/ export); added AppIconPreviewDark
  from AppIcon-dark.png so the mock shows the correct icon per appearance
- Re-captured 9-widgets-dark + 10-widgets-light
- 95/95 tests green; Release IPA rebuilt + re-served

FuelBoard/Assets.xcassets/AppIconPreviewDark.imageset/Contents.json

@@ -0,0 +1,13 @@
+{
+  "images" : [
+    {
+      "filename" : "AppIconPreviewDark.png",
+      "idiom" : "universal",
+      "scale" : "1x"
+    }
+  ],
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

FuelBoard/WidgetMockScreen.swift

@@ -6,6 +6,8 @@ import WidgetKit
 /// code the widget extension renders) at small + medium sizes. Used for App
 /// Store screenshot captures; not reachable from the UI.
 struct WidgetMockScreen: View {
+    @Environment(\.colorScheme) private var colorScheme
+
     var body: some View {
         ZStack {
             // Real iPhone wallpaper (extracted from the iOS 26.3 sim runtime —
@@ -16,9 +18,11 @@ struct WidgetMockScreen: View {
                 .ignoresSafeArea()
 
             VStack(alignment: .leading, spacing: 26) {
-                // App icon + name, home-screen style
+                // App icon + name, home-screen style. Uses the SAME artwork
+                // the app ships (AppIcon.appiconset), with the dark variant
+                // when the device is in dark mode — matching iOS behaviour.
                 HStack(spacing: 16) {
-                    Image("AppIconPreview")
+                    Image(colorScheme == .dark ? "AppIconPreviewDark" : "AppIconPreview")
                         .resizable()
                         .frame(width: 76, height: 76)
                         .clipShape(RoundedRectangle(cornerRadius: 17, style: .continuous))