Consolidate and organize documentation architecture

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

Audited all living docs: checker green, no dangling ADR cites, no stale specs/trackers, no duplicates, all docs ≤3 hops from CLAUDE.md. The 9 uncited ADRs still govern live code. Nothing to delete; no PR.