fix: resolve Photino window icon against app base directory

The icon path was relative and resolved against the working directory
(e.g. the directory the AppImage was launched from) rather than the
install directory, crashing on startup. Resolve it against
AppDomain.BaseDirectory, consistent with the wwwroot file provider.

Author: LucHeart

Desktop/Platforms/Photino/PhotinoEntryPoint.cs

@@ -84,8 +84,12 @@ private static void Start(CliOptions config)
 
         var app = builder.Build();
 
+        // Resolve the icon against the app's base directory; the working directory is
+        // wherever the AppImage was launched from (e.g. ~/Downloads), not the install dir.
+        var iconFile = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "wwwroot", "images", "Icon512.png");
+
         app.MainWindow
-            .SetIconFile("wwwroot/images/Icon512.png")
+            .SetIconFile(iconFile)
             .SetTitle("OpenShock Desktop");
 
         app.MainWindow.MinHeight = 600;