Reorg AI content nav in Guides

[myronkaifung]

No description provided.

[greptile-apps]

Confidence Score: 5/5

The PR appears safe to merge.

No blocking failure remains; the previously broken URLs now have redirects to the moved pages.

Important Files Changed

Filename	Overview
docs.json	Reorganizes AI navigation and adds redirects covering the moved guide routes.
guides/guides-by-topic/features.mdx	Updates AI feature cards to point to the reorganized guide paths.
guides/guides-by-use-case.mdx	Removes AI guides from the former use-case section after their navigation move.

_{Reviews (2): Last reviewed commit: "add redirects, move biz context and trus..." | Re-trigger Greptile}