context: Document Claude mutation-scope adapter contract

Record the shipped Claude mutation-scope adapter as durable repository context.
Add its scope model, identity derivation, fail-closed write-ahead behavior, cleanup and recovery rules, and unsupported background-shell boundary, then update the related runtime, routing, overview, architecture, map, raw-hook, and plan references.
Plan: claude-mutation-scope-integration, T09

Co-authored-by: SCE <sce@crocoder.dev>

Author: davidabram