Add Go demo with isolated CI and manual production release

build/Dockerfile

@@ -0,0 +1,21 @@
+FROM docker.io/library/golang:1.25.14-bookworm@sha256:c268a04d59aea0b180ed9946a658cfab9e7b3391dc90eed6e4969ccff98c851f AS build
+ENV GOTOOLCHAIN=local CGO_ENABLED=0
+WORKDIR /src
+COPY src/go.mod ./
+RUN --mount=type=cache,target=/go/pkg/mod go mod download
+COPY src/ ./
+RUN --mount=type=cache,target=/root/.cache/go-build \
+    test -z "$(gofmt -l .)" \
+    && go test ./... \
+    && go vet ./... \
+    && go build -trimpath -ldflags='-s -w' -o /out/demo .
+
+FROM scratch AS runtime
+ARG SOURCE_REVISION
+LABEL org.opencontainers.image.source="https://git.dever.cc/rabin/demo" \
+      org.opencontainers.image.revision=$SOURCE_REVISION
+COPY --from=build /out/demo /demo
+USER 65532:65532
+ENV PORT=8080
+EXPOSE 8080
+ENTRYPOINT ["/demo"]