feat: add harness runner (scenario executor, alert receiver, action executor, judge, revert)

harness/Dockerfile

@@ -0,0 +1,15 @@
+# harness runner (self-healing lab, experiment design 5). Built with Cloud Build into the public Artifact Registry.
+FROM golang:1.27.1-alpine AS build
+WORKDIR /src
+ENV CGO_ENABLED=0 GOFLAGS=-mod=mod
+COPY go.mod go.sum ./
+RUN go mod download
+COPY . .
+RUN go build -trimpath -ldflags="-s -w" -o /out/harness .
+
+FROM alpine:3.22
+RUN apk add --no-cache ca-certificates && adduser -D -u 10001 harness
+USER 10001
+COPY --from=build /out/harness /usr/local/bin/harness
+EXPOSE 8080
+ENTRYPOINT ["/usr/local/bin/harness"]