[jasperblues]

Problem: the Postgres section says everything but vector search works without pgvector; Drivine fails startup ensuring the vector index instead.

Before

• "Without pgvector everything works except the message vector index and vector search."
• Guide "on any of the four databases".

Now

• Without pgvector, set embabel.chat.store.vector-index.enabled: false, or startup fails ensuring the index.
• Guide on Neo4j, FalkorDB, Memgraph, Oracle or Postgres (Run on Postgres: Drivine 0.2.0, a postgres profile and tests guide#57).