Add folder sidebar navigation section to Media Library docs

[pwizla]

This PR updates documentation based on strapi/strapi#26551.

Generated automatically by the docs self-healing workflow.
Review before merging.

What changed

Added a new "Navigating with the folder sidebar" section (H4) inside ### Organizing assets with folders in docusaurus/docs/cms/features/media-library.md.

The section documents:

• The persistent folder sidebar that displays the full folder hierarchy
• How the sidebar loads from GET /upload/folder-structure
• Folder selection behavior and ?folder= URL parameter sync
• Automatic ancestor expansion for the active folder
• Redirect to root on invalid/missing folder ID

Also updated the :::note in #### Adding folders to remove the now-stale claim that the Media Library has no visual hierarchy indication.

TODOs for reviewer

• Feature flag: Confirm whether this sidebar requires enabling a future flag for the revamped Media Library. If it does, add the appropriate flag documentation and badge. If it's GA, remove the <!-- TODO --> comment.
• Screenshot: Consider adding a screenshot showing the sidebar in context.
• Stale note: The <!-- TODO --> comment on the Adding folders note flags it for removal/update once the sidebar is confirmed GA.

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Project	Deployment	Actions	Updated (UTC)
documentation	Ready	Preview, Comment	Jun 19, 2026 8:34am

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