Enhance close button in PublicFileViewer: add custom button style to remove splash effect

b0esche_cloud/lib/pages/public_file_viewer.dart

@@ -229,6 +229,17 @@ class _PublicFileViewerState extends State<PublicFileViewer> {
         actions: [
           IconButton(
             icon: const Icon(Icons.close, color: AppTheme.primaryText),
+            style: ButtonStyle(
+              splashFactory: NoSplash.splashFactory,
+              overlayColor: WidgetStateProperty.resolveWith<Color?>((
+                Set<WidgetState> states,
+              ) {
+                if (states.contains(WidgetState.pressed)) {
+                  return Colors.transparent;
+                }
+                return null;
+              }),
+            ),
             onPressed: () => context.go('/'),
           ),
         ],