New hypothesis generator method (raised by Jason)

## Memo

**Jason raised implementing a new hypothesis generator method** — a new approach to how hypotheses are generated — in addition to the KG-based pre-populated dataset strategy (#7).

This issue is a lightweight placeholder to track the item; the concrete method/design is TBD.

**Related:** #7 (Jason's KG-based pre-populated dataset requirement).

This issue names no files, tests, or entry points; start with the related #7 to understand the existing KG-based strategy. The concrete method and design are still TBD, so the work is not ready to start; done means an agreed design for the new hypothesis generator is documented.

Written by the indexing model from the issue text.