fix: devKeys support in flutter by conditionally including credentials

Author: ChiragAgg5k

templates/flutter/lib/src/client_browser.dart.twig

@@ -112,7 +112,6 @@ class ClientBrowser extends ClientBase with ClientMixin {
     if (cookieFallback != null) {
       addHeader('x-fallback-cookies', cookieFallback);
     }
-    _httpClient.withCredentials = true;
   }
 
   @override
@@ -192,11 +191,21 @@ class ClientBrowser extends ClientBase with ClientMixin {
   }) async {
     await init();
 
+    // Combine headers to check for dev key
+    final combinedHeaders = {..._headers!, ...headers};
+    
+    // Only include credentials when dev key is not set
+    if (combinedHeaders['X-Appwrite-Dev-Key'] == null) {
+      _httpClient.withCredentials = true;
+    } else {
+      _httpClient.withCredentials = false;
+    }
+
     late http.Response res;
     http.BaseRequest request = prepareRequest(
       method,
       uri: Uri.parse(_endPoint + path),
-      headers: {..._headers!, ...headers},
+      headers: combinedHeaders,
       params: params,
     );
     try {