feat(command-injection): Add command injection example

backend/Dockerfile

@@ -1,5 +1,10 @@
 FROM node:23-slim
 
+RUN apt update && \
+    apt install -y iputils-ping \
+    && apt clean \
+    && rm -rf /var/lib/apt/lists/*
+
 WORKDIR /app
 COPY . .
 RUN npm install