ANU-17: Bento readiness gate for ANU-14

This change delivers the Bento-owned editor capabilities that ANU-14 needs before CMS implementation can continue: host-triggered save requests, stable surface-and-slide focus, and a deterministic packaged Signal/Paper template catalog.

The change does not authorize a CMS workaround. Product Main records the contract and acceptance gate, while one repository-scoped anuva-bento child will implement, document, test, and publish the reviewed 1.1.0 artifacts.

Change artifacts

• Change brief
• Repository impact
• Implementation issues
• Progress
• Completion review

Current state

• Linear parent: ANU-17
• Priority: High
• Status: In Progress; completion review approved, completion PR pending
• Planning PR: Product Main #17, merged
• Implementation: ANU-18 is Done; Bento PR #6 is merged
• Completion branch: codex/anu-17-anuva-bento-fix-for-anu-14-readiness-gate-completion
• Dependent work: ANU-14 may consume the reviewed 1.1.0 boundary under its own approved workflow
• Canonical publication: not published