Clean up and consolidate 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: check_context passes; all 142 ADRs have live homes and no history prose; 8 unreferenced-ADR and 5 routing advisories are false positives; no stale specs or trackers. Nothing to delete. No PR. Memory: none applied.