v0.56.1

Fix update_summary corrupting embeddings via ChromaDB default embedding function.

update_summary() passed documents= to ChromaDB without explicit embeddings, triggering ChromaDB's DefaultEmbeddingFunction (384d all-MiniLM-L6-v2) which replaced the configured provider's embeddings (e.g. 768d nomic-embed-text). Now fetches and re-passes existing embeddings to prevent re-embedding.