Remove external-reference smoke test

Delete data/embeddings/hf_portal_central_smoke_20260728_v1

Delete data/embeddings/hf_portal_category_modality_smoke_20260728_v3

Delete data/community_validation/external_reference_smoke_20260727_v1

Accept hf_portal_category_modality_smoke_20260728_v3 from HF PR #6

Accept hf_portal_central_smoke_20260728_v1 from HF PR #3

Publish submissions/external_reference_smoke_20260727_v1.yaml

Initialize empty community registry

Remove smoke-test community manifest

Remove smoke-test community registry

Remove completed smoke-test package

Publish submissions/smoke_test_embedding.yaml