Clean up and organize stale documentation

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 scrub: folded ADR-0024 into 0012, trimmed restated/history text in ADRs, fixed stale citation, added router keywords. Quick gate green; PR #7313 queued to merge lane. Deferred: move package-distribution doc, further ADR trims. Memory: none applied.