Scrub Stale Documentation via CLAUDE.md Router

Use context architecture skill to scrub all old documentation, including instructions, specs, trackers, ADRs - delete everything superseeded and stale, remove references to historical decisions, delete duplicates, single home everything and make sure all documentation is accessible from CLAUDE.md router in a few steps

Partial scrub merged (PR #5506, full gate green): ADR fixes, deleted finished deploy runbook, removed history/stale paths. Deferred: bulk ADR shortening/merges, test-perf dead-ends, integration dedupe. Router had no orphans. Deploy not watched.