AI: Add in-game galaxy map as MapEditor canvas background

ZeroSpace/ZeroSpace.MapEditor/Services/MapBackground.cs

@@ -0,0 +1,39 @@
+using Microsoft.Maui.Graphics;
+using Microsoft.Maui.Storage;
+
+namespace ZeroSpace.MapEditor.Services;
+
+/// <summary>
+/// Loads the in-game galaxy map screenshot as the canvas background.
+/// The PNG lives in Resources/Raw and is deployed as a MauiAsset.
+/// </summary>
+public static class MapBackground
+{
+    private const string AssetName = "galaxymap.png";
+
+    public static async Task<IImage?> LoadAsync()
+    {
+        try
+        {
+            await using var packageStream = await FileSystem.OpenAppPackageFileAsync(AssetName);
+            // Copy into memory and leave the buffer undisposed: some platform
+            // image implementations read from the stream lazily.
+            var buffer = new MemoryStream();
+            await packageStream.CopyToAsync(buffer);
+            buffer.Position = 0;
+#if WINDOWS
+            return new Microsoft.Maui.Graphics.Platform.PlatformImage(buffer);
+#elif MACCATALYST
+            return new Microsoft.Maui.Graphics.Platform.PlatformImage(buffer);
+#else
+            return null;
+#endif
+        }
+        catch
+        {
+            // No map image available (missing asset, unsupported platform):
+            // the editor works fine without the background.
+            return null;
+        }
+    }
+}