Adds ARCH-CONSOLIDATION-2026-04.md as the authoritative reference for the
upcoming 8-workstream architecture consolidation sprint: purpose registry
cleanup, ULID consistency, JSON column split, binding infrastructure,
FormBindingApplicator, single-SPA consolidation to crewli.app, observability
foundation, docs consolidation.
Sprint scope, leading principles, workstream ordering, and chat-transition
protocol are captured in the document. Follow-up chats will start from this
document as primary context.
Also updates BACKLOG.md with an active-sprint marker pointing to the briefing.
