Consolidate stale docs into 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

Context-architecture audit found nothing stale, duplicated or unreachable; docs already single-homed and routed from CLAUDE.md in ≤3 hops. No change made, no PR.