chore: add dockerfile and ci

dockerfile

@@ -0,0 +1,22 @@
+FROM golang:1.26.1 as builder
+
+WORKDIR /app
+
+COPY . .
+ENV CGO_ENABLED=0
+ENV GIN_MODE=release
+RUN --mount=type=cache,target=/go/pkg/mod \
+  --mount=type=cache,target=/root/.cache/go-build \
+  go mod download && \
+  go build -ldflags "-s -w" -o backend ./cmd/main.go
+
+FROM alpine:3.23.0
+
+RUN apk add --no-cache curl openssl bash
+
+COPY --from=builder /app/backend .
+
+EXPOSE 8080
+HEALTHCHECK --interval=30s --timeout=30s --start-period=5s --retries=3 CMD [ "curl --fail http://localhost:8080/health" ]
+
+CMD ["./backend"]