ANU-18: Bento Host Save, Stable Focus, and Template Catalog

This change closes the Bento editor readiness gaps identified by Product Main ANU-17 for the downstream ANU-14 integration.

• Implementation Plan
• Implementation Log
• Completion Report
• Linear: ANU-18
• Product Main source: docs/changes/2026-07-27-anu-17-bento-readiness-gate/index.md
• Product Main review preview: https://main1.girishd.com/changes/2026-07-27-anu-17-bento-readiness-gate/
• Draft PR: Shoonya-Game-Technologies/anuva-bento#6
• Status: implementation and verification complete; In Review on the linked draft PR