fix(backend): auto-submit dataset version after exporting workflow results

[seongjinyoon]

What changes were proposed in this PR?

Problem:
When exporting workflow execution results to a dataset, the exported files were only uploaded to the LakeFS staging area (uncommitted workspace). Users had to manually navigate to the Datasets tab, select the dataset, and click "Submit" to commit the staged files as a new dataset version.

This PR removes that manual step by automatically creating a dataset version after the file upload completes.

Changes:

• Added a new commitDatasetVersion() method in ResultExportService that calls the file service's /{did}/version/create endpoint to commit staged files as a new dataset version.
• In exportToDataset(), after all operator results are uploaded successfully, the method now calls commitDatasetVersion() for each target dataset.
• Added ENV_FILE_SERVICE_CREATE_DATASET_VERSION_ENDPOINT environment variable in EnvironmentalVariable for configuring the version creation endpoint URL.

Any related issues, documentation, discussions?

#4348

How was this PR tested?

Manually tested.

Screen.Recording.2026-04-05.at.11.04.42.AM.mov

Was this PR authored or co-authored using generative AI tooling?

Revised with Claude Code.

[chenlica]

@seongjinyoon Per our recent discussion, please create an issue and describe the problem there. Then cite the issue in this PR. After that, I will assign people to review it.