feat: add Dockerfile and docker-compose for containerized deployment

Dockerfile

@@ -0,0 +1,12 @@
+FROM golang:1.26.4-alpine AS builder
+
+WORKDIR /app
+COPY go.mod go.sum ./
+RUN go mod download
+COPY . .
+RUN CGO_ENABLED=0 go build -o /divad ./cmd/divad
+
+FROM gcr.io/distroless/static-debian13:nonroot
+COPY --from=builder /divad /divad
+EXPOSE 8080
+ENTRYPOINT ["/divad"]