feat: start recode backend to golang

backend/Dockerfile

@@ -0,0 +1,18 @@
+FROM golang:1.25.6 AS builder
+
+
+WORKDIR /app
+
+COPY  . .
+ENV CGO_ENABLED=0
+
+RUN go build -ldflags "-s -w" -o backend ./cmd/main.go
+
+
+FROM alpine:3.23.0
+
+COPY --from=builder /app/backend .
+
+EXPOSE 8080
+
+CMD ["./backend"]