Remove keys volume mount and add install script

- Remove /etc/provisioning/keys mount (ephemeral keys are in-memory now)
- Remove /etc/provisioning VOLUME from Dockerfile
- Add deploy/install.sh that creates config files before docker compose up,
  preventing Docker from creating directories in place of missing bind mounts
- Update README with install script usage

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

deploy/Dockerfile

@@ -19,10 +19,10 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
 
 COPY --from=builder /provisioning /usr/local/bin/provisioning
 
-RUN mkdir -p /data /etc/provisioning/keys
+RUN mkdir -p /data
 
 EXPOSE 8080
-VOLUME ["/data", "/etc/provisioning"]
+VOLUME ["/data"]
 
 ENTRYPOINT ["/usr/local/bin/provisioning"]
 CMD ["-config", "/etc/provisioning/provisioning.yaml"]