Consolidate and clean up 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 ADRs and living docs (already near-clean); fixed 3 ADR entries, trimmed duplicated skill prose, removed volatile placeholders. Quick gate green; PR #7943 queued to merge lane. ADR-0101 duplicate left (needs code repoint). Memory: none applied.