Foundation for audit #4 (cross-device reactivity). Long-lived SSE
subscription exposed as a process-wide SharedFlow<LiveEvent>; gated
on having a session cookie (opens on sign-in, closes on sign-out).
Mirrors flutter_client/lib/shared/live_events_provider.dart in
behavior — no client-side timeout (server heartbeats every 15s),
no explicit reconnect-with-backoff in v1 (auth transitions re-open).
LiveEvent carries kind / userId / data (JsonObject); consumers
deserialize the payload per event kind they handle.
Force-injected into MinstrelApplication via the same pattern as
MutationReplayer / SyncController / ResumeController /
PlayEventsReporter so the singleton constructs at app start.
okhttp-sse was already on the classpath; no new deps.
No consumers yet — LiveEventsDispatcher + per-screen subscribers
land in follow-up commits.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
bvandeusen
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