add real-time infrastructure (#137)

* setup infra for pusher service

* setup client sdk for pusher service

* fix: ping parse failure

* fix: send pong back to client

avoid disconnections every 2.5 minutes

* increase replicas

* feat: show presence and compose indicator

go/Makefile

@@ -46,7 +46,7 @@ migrate-prod:
 	SKAFFOLD_DEFAULT_REPO=$(PROD_REPO) skaffold run -p migrations --kube-context prod --tail
 
 # ---- Deploy ----
-# Use MODULE=orion or MODULE=worker to deploy a single service, e.g.:
+# Use MODULE=orion or MODULE=worker or MODULE=pusher to deploy a single service, e.g.:
 #   make deploy-dev MODULE=orion
 
 .PHONY: deploy-dev