P8.1: Add scratch-based Dockerfile with OCI labels

- Uses FROM scratch for minimal image size (14.2 MB)
- Includes OCI labels: source, version, revision, licenses
- Exposes ports 7700 (main) and 9090 (metrics)
- Static musl binary for zero libc dependency

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Dockerfile

@@ -0,0 +1,13 @@
+# miroir-proxy - scratch base, static musl binary
+FROM scratch
+ARG VERSION=0.1.0
+ARG REVISION=unknown
+LABEL org.opencontainers.image.source=https://github.com/jedarden/miroir
+LABEL org.opencontainers.image.version=${VERSION}
+LABEL org.opencontainers.image.revision=${REVISION}
+LABEL org.opencontainers.image.licenses=MIT
+
+COPY miroir-proxy-linux-amd64 /miroir-proxy
+EXPOSE 7700 9090
+ENTRYPOINT ["/miroir-proxy"]
+CMD ["--config", "/etc/miroir/config.yaml"]