Placeholder so `tests/perf/lubm/data/lubm-10/` exists in fresh clones.

The actual LUBM-10 dataset is **NOT** here — it lives in the docker
named volume `pgrdf-lubm-data`, at the in-volume path:

    /data/lubm-10/
      ├── raw/             (UBA OWL/RDF-XML, 189 files, ~101 MB)
      ├── nt/lubm-10.nt    (concatenated N-Triples, ~195 MB,
      │                    1,316,700 triples at -seed 0)
      └── ttl/lubm-10.ttl  (compact Turtle, ~106 MB)

To (re)materialise:

    just lubm-build              # one-time, ~30s, image ~295 MB
    just lubm-gen 10             # ~10s, populates the volume

To inspect:

    docker run --rm -v pgrdf-lubm-data:/data alpine:3.20 \
        sh -c "wc -l /data/lubm-10/nt/lubm-10.nt"

To free:

    just lubm-clean              # removes the volume

The TF-10 runner (`tests/perf/lubm/run-lubm.sh`) mounts the volume
into a one-shot postgres+pgrdf sidecar for ingest; nothing on the
host filesystem needs to live under this directory. See
`../README.md` for the broader TF-12 intake design.
