[Feature bug] Media gallery is shared resource instead of a single tenant

For now, Media gallery is a shared library for all the users using Creative studio

**Problem:**
There are folks working on confidential projects who do not want to share the content with other teams

**Expected behavior:**
We would like to have a separate workspace where the media gallery is isolated to individual user assests and not as a shared pool

The issue does not name files, tests, or an entry point. Start by locating the media gallery implementation and its current shared-library boundary, then confirm the isolation model and acceptance cases with maintainers. Done means assets are no longer visible across users or teams while remaining available within the owning workspace.

Written by the indexing model from the issue text.