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/Dockerfile.pusherservice

@@ -0,0 +1,22 @@
+# golang two stage build
+FROM golang:1.25 AS first-stage
+
+WORKDIR /app
+
+COPY go.mod go.sum ./
+RUN go mod download && go mod verify
+
+COPY . .
+
+WORKDIR /app/cmd/pusherservice
+RUN CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -o main
+RUN ls
+
+FROM alpine:latest AS second-stage
+# for health check
+RUN apk --no-cache add curl
+
+WORKDIR /app
+COPY --from=first-stage /app/cmd/pusherservice .
+RUN echo "copied over binary to production stage"
+CMD ["./main"]