Clean up and organize all documentation systematically

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 docs per context-architecture; nothing stale to remove (no trackers/archives, ADRs all live with code homes, no dup prose, router reachable, check_context passes). No PR. Memory: none applied.