Consolidate and clean 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 docs: already history-free (ADR register clean, no archives/active specs, all ADR homes resolve, checker green, router-reachable). Removed task-number provenance from risk register. Quick gate green; PR #7685 queued. No UI affected. Report not uploaded. Memory: none applied.