create .cache in user directory

Dockerfile

@@ -18,6 +18,8 @@ RUN apt-get update -qq && apt-get install -y --no-install-recommends \
   && apt-get clean
 
 COPY vetiver_renv.lock renv.lock
+# Create the .cache directory and give appuser permission to write to it
+RUN mkdir -p /home/appuser/.cache && chown -R appuser:appuser /home/appuser/.cache
 
 RUN Rscript -e "install.packages('renv')"
 RUN Rscript -e "renv::restore()"