Clean and consolidate outdated documentation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 PR #6872 queued: ADR narration/duplication trimmed, retired Gemini research deleted, history narration removed, Jira cookbook single-homed. Quick gate green. Deferred: ADR-0035 kill-path code defect, further dedupes, package-distribution tracker. Memory: none applied.