knn cleanups and tests

tests/correctness/build.py

@@ -0,0 +1,16 @@
+import numpy as np
+import duckdb
+db = duckdb.connect(":memory:")
+
+result = db.execute(
+"""
+  select
+    -- _id,
+    -- title,
+    -- text as contents,
+    embedding::float[] as embeddings
+  from "hf://datasets/Supabase/dbpedia-openai-3-large-1M/dbpedia_openai_3_large_00.parquet"
+"""
+).fetchnumpy()['embeddings']
+
+np.save("dbpedia_openai_3_large_00.npy", np.vstack(result))