Hub runtime split with managed hobby data (Always Free alternative)

Single-VM Compose on Oracle remains the default Hub runtime path (ADR 0003). As an optional alternative for intermittent maintainer dogfood, we split compute: Oracle Always Free AMD micro #1 runs Caddy + API only; AMD micro #2 runs Celery worker + Beat and may be stopped when not testing; Postgres and Redis come from free hobby providers (default: Neon + Upstash) via shared env on both VMs; SMTP stays external. Artifacts live under docs/deployment/hub-runtime/split/ (compose.api.yml, compose.worker.yml, separate bootstraps) so parent compose.yml / bootstrap.sh stay the one-box path. True free PaaS background workers (Render/Koyeb) were rejected — they are paid or web-only. Four-way self-hosted DB/Redis/worker/API on Always Free was rejected for RAM and disk limits.