Download Docker Compose plugin directly from GitHub

docker-compose-plugin isn't in Debian repos, need to download
the binary directly from Docker's GitHub releases.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

Dockerfile

@@ -4,15 +4,20 @@ FROM python:3.11-slim
 WORKDIR /app
 
 # Install system dependencies
-# - Docker CLI + Compose plugin for docker executor
+# - Docker CLI for docker executor
 # - curl for health checks
 RUN apt-get update && \
     apt-get install -y --no-install-recommends \
         docker-cli \
-        docker-compose-plugin \
         curl \
     && rm -rf /var/lib/apt/lists/*
 
+# Install Docker Compose plugin (not in Debian repos, download from Docker)
+RUN mkdir -p /usr/local/lib/docker/cli-plugins && \
+    curl -SL "https://github.com/docker/compose/releases/download/v2.32.1/docker-compose-linux-x86_64" \
+        -o /usr/local/lib/docker/cli-plugins/docker-compose && \
+    chmod +x /usr/local/lib/docker/cli-plugins/docker-compose
+
 # Copy requirements first for layer caching
 COPY requirements.txt .