ANU-19: Repository-scoped change workflow

This change replaces issue-free Direct Maintenance as the normal path for repository-local work. A matching request may select anuva-repository-change implicitly, but every external mutation remains behind the same visible approval boundaries used by planned Linear implementation.

The workflow first performs a read-only eligibility and Product Main impact preflight. Escalate returns an exact Product Main intake without creating repository-change state or artifacts. Not required and Required may create one standalone, repository-labeled Linear issue directly in In Progress, produce an approved implementation plan, deliver the repository PR and any required Product Main documentation companion PR, verify cleanup and local base synchronization, and only then mark the issue Done.

Change artifacts

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

Current state

• Linear parent: ANU-19
• Priority: Medium
• Status: In Progress; every implementation child is Done and the completion review is approved for completion-phase PR delivery
• Completion branch: codex/anu-19-introduce-repository-scoped-change-workflow-and-completion
• Delivered scope: Product Main foundation plus repository-local adoption in Bento, CMS, Python, and Unity
• Canonical publication: not published