chore(build): 镜像内构建 hfb-rebate-backfill 以便生产执行返利补发

补发脚本需要在生产镜像里可直接执行，与 hfb-storage-migrate 保持同一构建/拷贝方式。

backend/Dockerfile

@@ -19,6 +19,10 @@ RUN --mount=type=cache,target=/go/pkg/mod \
 RUN --mount=type=cache,target=/go/pkg/mod \
     --mount=type=cache,target=/root/.cache/go-build \
     CGO_ENABLED=0 GOOS=linux go build -o /out/hfb-storage-migrate ./cmd/storage-migrate
+# 一次性运维脚本：线下提号邀请返利补发（默认预演，-apply 才写库）
+RUN --mount=type=cache,target=/go/pkg/mod \
+    --mount=type=cache,target=/root/.cache/go-build \
+    CGO_ENABLED=0 GOOS=linux go build -o /out/hfb-rebate-backfill ./cmd/rebate-backfill
 
 FROM alpine:3.22
 
@@ -34,6 +38,7 @@ RUN sed -i 's#https\?://dl-cdn.alpinelinux.org/alpine#https://mirrors.aliyun.com
     && chown app:app /app/logs
 COPY --from=build /out/hfb-api /app/hfb-api
 COPY --from=build /out/hfb-storage-migrate /app/hfb-storage-migrate
+COPY --from=build /out/hfb-rebate-backfill /app/hfb-rebate-backfill
 COPY --from=build /go/bin/goose /app/goose
 COPY --from=build /src/migrations /app/migrations
 USER app:app