proxy model download through model server/central

## Description

At the moment every web-client/browser needs access through firewalls/proxies to download the model using central from the original URL as well as to central.
Instead of that it would be possible that just the central-server is configured to access all necessary network-resources.
The client could just call an URL of the central-server and the server would stream the model-download to the client

This would open the door to some future improvements like:

Authentication/Authorisation of downloads managed by central. (OAuth-plugin, Kerberos-plugin)
central could be used as a Mirror or for Caching of remote models - similar to how Nexus can be configured when using maven. Nexus is used often this way for caching or to control which artifacts are used inside of a company.
uploading models with central without granting access for all web-clients to whatever storage central is using. so different storage strategies would be possible.
single point to configure firewall access. Would also be nice for cloud based services using models.
just a few ideas from a DevOp perspective

Will this change the current api? How?

Who will benefit from this enhancement?

## References
- list reference and related literature
- list known implementations

Start by reviewing the current central and web-client model-download flow and its API boundaries. Define the required proxy behavior and API impact, then verify that clients can obtain models through central without direct access to the original URL; authentication, caching, and upload strategies remain future considerations.

Written by the indexing model from the issue text.