Add apps warmup on build

Dockerfile

@@ -5,6 +5,7 @@ ENV LIVEBOOK_APP_SERVICE_URL "https://huggingface.co/spaces/$SPACE_AUTHOR_NAME/$
 ENV LIVEBOOK_UPDATE_INSTRUCTIONS_URL "https://livebook.dev"
 ENV LIVEBOOK_WITHIN_IFRAME "true"
 ENV LIVEBOOK_APPS_PATH "/public-apps"
+ENV LIVEBOOK_APPS_PATH_WARMUP "manual"
 ENV LIVEBOOK_DATA_PATH "/data"
 ENV LIVEBOOK_PORT 7860
 
@@ -13,3 +14,4 @@ USER root
 COPY public-apps/ /public-apps
 RUN mkdir -p /data
 RUN chmod 777 /data
+RUN /app/bin/warmup_apps.sh