refactor chunking and embedding into their own modules

tests/test_embed.py

@@ -3,7 +3,7 @@ from __future__ import annotations
 import unittest
 from unittest.mock import patch
 
-from chromy.embed import embed
+from chromy.embedding import embed
 
 
 class EmbedTest(unittest.TestCase):
@@ -12,7 +12,7 @@ class EmbedTest(unittest.TestCase):
 
     def test_embed_pairs_text_with_list_embeddings(self) -> None:
         with patch(
-            "chromy.embed.DefaultEmbeddingFunction",
+            "chromy.embedding.service.DefaultEmbeddingFunction",
             return_value=lambda chunks: ((1.0, 2.0), (3.0, 4.0)),
         ):
             result = embed(["first", "second"])