*: optimize Dockerfile

Dockerfile

@@ -1,14 +1,18 @@
 # Container for building Go binary.
 FROM golang:1.23.2-bookworm AS builder
 # Install dependencies
-RUN apt-get update && apt-get install -y build-essential git
+RUN apt-get update && apt-get install -y --no-install-recommends build-essential git
+
 # Prep and copy source
 WORKDIR /app/charon
+
 COPY . .
+
 # Populate GO_BUILD_FLAG with a build arg to provide an optional go build flag.
 ARG GO_BUILD_FLAG
 ENV GO_BUILD_FLAG=${GO_BUILD_FLAG}
 RUN echo "Building with GO_BUILD_FLAG='${GO_BUILD_FLAG}'"
+
 # Build with Go module and Go build caches.
 RUN \
    --mount=type=cache,target=/go/pkg \
@@ -18,30 +22,35 @@ RUN echo "Built charon version=$(./charon version)"
 
 # Copy final binary into light stage.
 FROM debian:bookworm-slim
-RUN apt-get update && apt-get install -y ca-certificates wget fio
+RUN apt-get update && apt-get install -y --no-install-recommends ca-certificates fio wget \
+  && rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*
 ARG GITHUB_SHA=local
 ENV GITHUB_SHA=${GITHUB_SHA}
+
 COPY --from=builder /app/charon/charon /usr/local/bin/
+
 # Don't run container as root
 ENV USER=charon
 ENV UID=1000
 ENV GID=1000
-RUN addgroup --gid "$GID" "$USER"
-RUN adduser \
+RUN addgroup --gid "$GID" "$USER" \
+  && adduser \
     --disabled-password \
     --gecos "charon" \
     --home "/opt/$USER" \
     --ingroup "$USER" \
     --no-create-home \
     --uid "$UID" \
-    "$USER"
-RUN chown charon /usr/local/bin/charon
-RUN chmod u+x /usr/local/bin/charon
+    "$USER" \
+  && chown "$USER" /usr/local/bin/charon \
+  && chmod u+x /usr/local/bin/charon
+
 WORKDIR "/opt/$USER"
-RUN chown charon "/opt/$USER"
 USER charon
+
 ENTRYPOINT ["/usr/local/bin/charon"]
 CMD ["run"]
+
 # Used by GitHub to associate container with repo.
 LABEL org.opencontainers.image.source="https://github.com/obolnetwork/charon"
 LABEL org.opencontainers.image.title="charon"