- Add RedisIoAdapter (shared/infra) for multi-instance Socket.IO fan-out
with graceful fallback to the in-memory IoAdapter when Redis is
unreachable.
- Pin Socket.IO heartbeat (pingInterval/pingTimeout/connectTimeout)
via env-tunable gateway options for reconnect stability.
- Expose Prometheus metrics on /notifications: goodgo_ws_connected_clients
(Gauge) and goodgo_ws_messages_total (Counter) with namespace/event/
direction labels. Wired through MetricsService and tracked across
connect/disconnect + emits.
- Unit tests: RedisIoAdapter connect/fallback/close, new MetricsService
WS helpers, and gateway metric increments/decrements on auth paths.
Co-Authored-By: Paperclip <noreply@paperclip.ing>
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