Improve devcontainer Dockerfile following best practices

- Use apt-get instead of apt for better script compatibility
- Add --no-install-recommends to reduce image size
- Add cleanup to remove apt cache
- Parameterize external tool versions with build args

.devcontainer/Dockerfile

@@ -4,7 +4,8 @@ ARG TZ
 ENV TZ="$TZ"
 
 # Install basic development tools and iptables/ipset
-RUN apt update && apt install -y less \
+RUN apt-get update && apt-get install -y --no-install-recommends \
+  less \
   git \
   procps \
   sudo \
@@ -19,7 +20,8 @@ RUN apt update && apt install -y less \
   iproute2 \
   dnsutils \
   aggregate \
-  jq
+  jq \
+  && apt-get clean && rm -rf /var/lib/apt/lists/*
 
 # Ensure default node user has access to /usr/local/share
 RUN mkdir -p /usr/local/share/npm-global && \
@@ -42,10 +44,11 @@ RUN mkdir -p /workspace /home/node/.claude && \
 
 WORKDIR /workspace
 
+ARG GIT_DELTA_VERSION=0.18.2
 RUN ARCH=$(dpkg --print-architecture) && \
-  wget "https://github.com/dandavison/delta/releases/download/0.18.2/git-delta_0.18.2_${ARCH}.deb" && \
+  wget "https://github.com/dandavison/delta/releases/download/${GIT_DELTA_VERSION}/git-delta_${GIT_DELTA_VERSION}_${ARCH}.deb" && \
-  sudo dpkg -i "git-delta_0.18.2_${ARCH}.deb" && \
+  sudo dpkg -i "git-delta_${GIT_DELTA_VERSION}_${ARCH}.deb" && \
-  rm "git-delta_0.18.2_${ARCH}.deb"
+  rm "git-delta_${GIT_DELTA_VERSION}_${ARCH}.deb"
 
 # Set up non-root user
 USER node
@@ -58,7 +61,8 @@ ENV PATH=$PATH:/usr/local/share/npm-global/bin
 ENV SHELL=/bin/zsh
 
 # Default powerline10k theme
-RUN sh -c "$(wget -O- https://github.com/deluan/zsh-in-docker/releases/download/v1.2.0/zsh-in-docker.sh)" -- \
+ARG ZSH_IN_DOCKER_VERSION=1.2.0
+RUN sh -c "$(wget -O- https://github.com/deluan/zsh-in-docker/releases/download/v${ZSH_IN_DOCKER_VERSION}/zsh-in-docker.sh)" -- \
   -p git \
   -p fzf \
   -a "source /usr/share/doc/fzf/examples/key-bindings.zsh" \

.devcontainer/devcontainer.json

@@ -3,7 +3,9 @@
   "build": {
     "dockerfile": "Dockerfile",
     "args": {
-      "TZ": "${localEnv:TZ:America/Los_Angeles}"
+      "TZ": "${localEnv:TZ:America/Los_Angeles}",
+      "GIT_DELTA_VERSION": "0.18.2",
+      "ZSH_IN_DOCKER_VERSION": "1.2.0"
     }
   },
   "runArgs": [