Organize Hub Xet docs

[rajatarya]

(...same changes as #1956 just put in new PR since messed up rebase...)

• reorganized Storage Backends page to be more Xet centric, have subpages, link to Xet Protocol pages.
• bumped Xet Protocol page to version 1.0.0
• Updated links to /storage-backends

[Copilot]

Pull Request Overview

This PR reorganizes the Xet storage documentation on the Hugging Face Hub by replacing the single "Storage Backends" page with a dedicated Xet section containing multiple focused subpages.

• Restructured storage documentation into a dedicated Xet section with individual pages for overview, usage, deduplication, legacy compatibility, and security
• Updated the Xet Protocol Specification to version 1.0.0 from the preliminary version
• Updated all internal links to point to the new Xet documentation structure

Reviewed Changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
docs/xet/index.md	Updated protocol version from 0.1.0 to 1.0.0
docs/hub/xet/*.md	Created dedicated pages for Xet overview, usage, deduplication, legacy compatibility, and security
docs/hub/storage-backends.md	Removed the original storage backends page
docs/hub/repositories.md	Updated link to point to new Xet index page
docs/hub/index.md	Updated statistics and links to new Xet documentation structure
docs/hub/_toctree.yml	Added hierarchical structure for Xet documentation pages
docs/hub/_redirects.yml	Updated redirect for xet path to new location

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[HuggingFaceDocBuilderDev]

The docs for this PR live here. All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.

[assafvayner]

[pcuenca]

Amazing! 🔥

[julien-c]

lets get this merged soon as it's starting to become hard to review (given number of reviewers/comments)

[rajatarya]

Merging this as I believe all the feedback has been addressed. Happy to take additional feedback and incorporate into next PR.

We will likely be adding some more images to Xet Protocol based on some visuals @seanses created recently.