Clean up and reorganize all documentation files

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 412 docs per the context-architecture playbook; nothing stale, duplicated or unreachable found, so no PR. Details in the report. Memory: none applied.