`duckdb` extension

[BERENZ]

We can use duckdb for search:

• faiss: https://duckdb.org/community_extensions/extensions/faiss.html
• and hnsw as in ragnar package

[BERENZ]

The goal is to move all calculations to duckdb, i.e.:

• creation of shingles / reading embeddings
• index build with vss/faiss + query
• pass to igraph for graph components