fix: install Docker CLI and mount socket for instance management

- Install docker-ce-cli and docker-compose-plugin in API Dockerfile
- Mount /var/run/docker.sock into API container
- Add appuser to docker group for socket permissions
- Fixes FileNotFoundError when deleting instances

apps/api/Dockerfile

@@ -16,16 +16,28 @@ RUN pip install --no-cache-dir --user -e ".[dev]"
 # Production stage
 FROM python:3.11-slim
 
-# Create non-root user
-RUN groupadd -r appgroup && useradd -r -g appgroup appuser
+# Create non-root user and add to docker group
+RUN groupadd -r appgroup && useradd -r -g appgroup appuser \
+    && groupadd -r docker || true \
+    && usermod -aG docker appuser
 
 WORKDIR /app
 
-# Install runtime dependencies
+# Install runtime dependencies including Docker CLI
 RUN apt-get update && apt-get install -y --no-install-recommends \
     libpq5 \
     git \
     netcat-openbsd \
+    ca-certificates \
+    curl \
+    gnupg \
+    && install -m 0755 -d /etc/apt/keyrings \
+    && curl -fsSL https://download.docker.com/linux/debian/gpg | gpg --dearmor -o /etc/apt/keyrings/docker.gpg \
+    && chmod a+r /etc/apt/keyrings/docker.gpg \
+    && echo "deb [arch="$(dpkg --print-architecture)" signed-by=/etc/apt/keyrings/docker.gpg] https://download.docker.com/linux/debian \
+    "$(. /etc/os-release && echo "$VERSION_CODENAME")" stable" > /etc/apt/sources.list.d/docker.list \
+    && apt-get update \
+    && apt-get install -y --no-install-recommends docker-ce-cli docker-compose-plugin \
     && rm -rf /var/lib/apt/lists/*
 
 # Copy dependencies from builder

docker-compose.traefik.yml

@@ -95,6 +95,7 @@ services:
       - repo_data:/data/repos
       - instance_data:/data/instances
       - avatar_uploads:/app/uploads
+      - /var/run/docker.sock:/var/run/docker.sock
     depends_on:
       postgres:
         condition: service_healthy