Batched embedding client (input as a list, batch 64 measured live at ~8-18
ms/chunk vs ~150-200 ms/chunk sequential through embed_chunk's
/api/embeddings) for jobs/mail-body-ingest -- embed_chunk stays the
single-text path for kb-query and paperless cyclic ingest. Validates the
response embedding count and each item's dimension (1024), raising
EmbeddingDimensionError (abort-run) on mismatch so a bad batch never silently
writes a mismatched vector (docs/kb/modules/05-faza-mailowa-plan.md, §4,
decision 5).