Scrub and Consolidate Documentation via CLAUDE.md

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

Docs already clean (Tier-1 green, ADRs live, all reachable). Marked 3 landed compliance controls live, dropped stale task refs. PR #4723 merged; Deploy not triggered (prose-only). Pre-existing test-stack host failure; one perf flake, passes alone.