docs(roadmaps): detailed 2026-04-17 plans for event bus, RAG, agent runtime, approval queue
Four grounded roadmaps superseding the scaffolded versions with
current-state audits, data models, week-by-week phase plans, tech-stack
decisions, and acceptance checklists. Execution order:
Event Bus (P0) unlocks Agent Runtime + RAG (P1 parallel), which unlock
Approval Queue (P1).
