fix: apple really wants this file as json (#4893)

diff --git a/app_dart/lib/src/request_handling/static_file_handler.dart b/app_dart/lib/src/request_handling/static_file_handler.dart
index 6e20a1b..45864e9 100644
--- a/app_dart/lib/src/request_handling/static_file_handler.dart
+++ b/app_dart/lib/src/request_handling/static_file_handler.dart

@@ -39,6 +39,10 @@
       '.smcbin': 'application/octet-stream',
     };
 
+    const mimeFileMap = {
+     'apple-app-site-association': 'application/json',
+    };
+
     final resultPath = filePath == '/' ? '/index.html' : filePath;
 
     /// The file path in app_dart to the files to serve
@@ -46,6 +50,7 @@
     final file = fs.file('$basePath$resultPath');
     if (file.existsSync()) {
       final mimeType =
+          mimeFileMap[path.basename(file.path)] ??
           mimeTypeMap[path.extension(file.path)] ??
           lookupMimeType(resultPath) ??
           'application/octet-stream';

diff --git a/app_dart/test/request_handling/static_file_handler_test.dart b/app_dart/test/request_handling/static_file_handler_test.dart
index 47f4fc1..69b54aa 100644
--- a/app_dart/test/request_handling/static_file_handler_test.dart
+++ b/app_dart/test/request_handling/static_file_handler_test.dart

@@ -124,5 +124,21 @@
       expect(body.contentType, isNotNull);
       expect(body.contentType!.mimeType, 'application/octet-stream');
     });
+
+    test('Basename overrides', () async {
+      fs.file('build/web/apple-app-site-association').writeAsStringSync('abc');
+      final staticFileHandler = StaticFileHandler(
+        '/apple-app-site-association',
+        config: config,
+        fs: fs,
+      );
+
+      final body = await tester.get(staticFileHandler);
+      expect(body, isNotNull);
+      final response = await decodeHandlerBody(body);
+      expect(response, 'abc');
+      expect(body.contentType, isNotNull);
+      expect(body.contentType!.mimeType, 'application/json');
+    });
   });
 }