Documentation cleanup and consolidation for accessibility

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

Docs scrub found the tree already clean (8 ADR candidates verified still implemented; no stale specs/trackers/orphans). One fix: ADR-0155 provenance trail removed. PR #7420 queued. Not done: line-by-line duplicate hunt in the 4 big policies. Memory: none applied.