Replaces hash pseudo-embeddings with BAAI/bge-small-en-v1.5 dense +
Qdrant/bm25 sparse legs fused by reciprocal-rank fusion over Qdrant
named vectors. Opt-in via QDRANT_EMBEDDINGS=1; offline fallback keeps
hash embedder relabeled qdrant-hash-fallback with an honest warning.
Live-verified semantically on a compendium subset. 27 new offline-safe
tests; pytest 713 passed / 25 skipped.
Co-Authored-By: Claude <[email protected]>