switch to using linkml-store

[cmungall]

See https://github.com/linkml/linkml-store

This would swap out the abstraction layer here https://github.com/monarch-initiative/curate-gpt/tree/main/src/curate_gpt/store

Note that no chromadb adapter is required - it's sufficient to use the default duckdb adapter (fast) and the llm lib. See https://linkml.io/linkml-store/examples/Semantic-Search.html