Add Docker configs

Dockerfile

@@ -0,0 +1,12 @@
+FROM golang:1.24-alpine AS builder
+WORKDIR /build
+COPY go.mod go.sum ./
+RUN go mod download
+COPY main.go ./
+RUN CGO_ENABLED=0 go build -trimpath -ldflags="-s -w" -o ctlog-uptime-exporter .
+
+FROM scratch
+COPY --from=builder /etc/ssl/certs/ca-certificates.crt /etc/ssl/certs/
+COPY --from=builder /build/ctlog-uptime-exporter /ctlog-uptime-exporter
+EXPOSE 9781
+ENTRYPOINT ["/ctlog-uptime-exporter"]