### Search before asking - [x] I searched in the [issues](https://github.com/apache/fluss/issues) and found nothing similar. ### Motivation Reduce the external IO operation when send source event to coordinator when FlinkSourceReader do snapshot state. See comment: https://github.com/apache/fluss/pull/2179#discussion_r2777638637 ### Solution _No response_ ### Anything else? _No response_ ### Willingness to contribute - [ ] I'm willing to submit a PR!