Incremental, phased plan (P0-P6) to put every subsystem on a shared
SubscriptionManager + RelayHealth foundation with unidirectional data flow,
fixing the O(videos x relays) REQ storms and emit-loop feedback identified
from real-environment logs. No feature removed; each phase shippable.
Co-Authored-By: Claude Opus 4.8 <[email protected]>
