put entrypoint in own file

Dockerfile.system

@@ -21,16 +21,7 @@ RUN uv pip install -r requirements.txt --system \
 RUN mkdir -p $DAGSTER_HOME
 
 # Create entrypoint that renders the dagster.yaml from a template
-RUN cat << 'EOF' > /entrypoint.sh
-#!/bin/sh
-set -e
-
-echo "Rendering dagster.yaml from template..."
-envsubst < dagster.yaml.template > dagster.yaml
-
-echo "Starting Dagster: $@"
-exec "$@"
-EOF
+COPY entrypoint.sh /entrypoint.sh
 RUN chmod +x /entrypoint.sh
 ENTRYPOINT ["/entrypoint.sh"]