feat: add docker image, auto-built using CI

Dockerfile

@@ -0,0 +1,21 @@
+FROM golang:1.18-alpine AS build
+
+ENV GOPRIVATE coopcloud.tech
+
+RUN apk add --no-cache make git gcc musl-dev
+
+COPY . /app
+
+WORKDIR /app
+
+RUN CGO_ENABLED=0 make build
+# RUN rm go.sum && go get -v -d -u ./... && \
+# 	make build
+
+RUN ls /app
+
+FROM scratch
+
+COPY --from=build /app/abra /abra
+
+ENTRYPOINT ["/abra"]