[dart_mcp_server] Update link of "Add to Cursor" button (#265)

Author: parlough

pkgs/dart_mcp_server/README.md

@@ -73,7 +73,7 @@ for configuring the server in Android Studio. -->
 
 ### Cursor
 
-[![Add to Cursor](https://cursor.com/deeplink/mcp-install-dark.svg)](https://cursor.com/install-mcp?name=dart&config=eyJ0eXBlIjoic3RkaW8iLCJjb21tYW5kIjoiZGFydCBtY3Atc2VydmVyIC0tZXhwZXJpbWVudGFsLW1jcC1zZXJ2ZXIgLS1mb3JjZS1yb290cy1mYWxsYmFjayJ9)
+[![Add to Cursor](https://cursor.com/deeplink/mcp-install-dark.svg)](cursor://anysphere.cursor-deeplink/mcp/install?name=dart&config=eyJ0eXBlIjoic3RkaW8iLCJjb21tYW5kIjoiZGFydCBtY3Atc2VydmVyIC0tZXhwZXJpbWVudGFsLW1jcC1zZXJ2ZXIgLS1mb3JjZS1yb290cy1mYWxsYmFjayJ9)
 
 The easiest way to configure the Dart MCP server with Cursor is by clicking the "Add to Cursor"
 button above.