feat: add container manager CLI commands and docker-compose overlay for admin container lifecycle

Dockerfile

@@ -3,9 +3,21 @@ FROM python:3.13-slim
 WORKDIR /app
 
 RUN apt-get update && apt-get install -y --no-install-recommends \
-    curl \
+    curl ca-certificates \
     && rm -rf /var/lib/apt/lists/*
 
+# Optional: the docker CLI so the (admin-only) container manager can drive the host
+# docker daemon. Off by default; the container compose override turns it on.
+ARG INSTALL_DOCKER_CLI=false
+RUN if [ "$INSTALL_DOCKER_CLI" = "true" ]; then \
+        install -m 0755 -d /etc/apt/keyrings && \
+        curl -fsSL https://download.docker.com/linux/debian/gpg -o /etc/apt/keyrings/docker.asc && \
+        chmod a+r /etc/apt/keyrings/docker.asc && \
+        echo "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.asc] https://download.docker.com/linux/debian bookworm stable" > /etc/apt/sources.list.d/docker.list && \
+        apt-get update && apt-get install -y --no-install-recommends docker-ce-cli && \
+        rm -rf /var/lib/apt/lists/* ; \
+    fi
+
 COPY pyproject.toml .
 
 COPY devplacepy/ devplacepy/