[Feature]: support HF_ENDPOINT environment variable

[bowerth]

What feature would you like to request?

It would be useful if the HF_ENDPOINT environment variable was supported for model download from Nexus repositories: https://help.sonatype.com/en/hugging-face-repositories.html

Is there any additional information you would like to provide?

No response

[pangwangshu]

Opened #667 to add support for HF_ENDPOINT.

The download path (ModelManagement.download_files_from_huggingface) now reads HF_ENDPOINT from the environment at call time and forwards it to the underlying Hugging Face Hub calls (snapshot_download, model_info, list_repo_tree), so it works even when the endpoint is set after huggingface_hub has already been imported (e.g. via Nexus-hosted HF repositories, as mentioned above).

PR: #667

[pangwangshu]

@NirantK Could you review #667? The implementation is complete, all CodeRabbit feedback is addressed, and tests pass. Ready for merge.