feat(ebook-search): implement async phrase matching for chunks and add ChunkPhraseHit model

tests/ebook_search/test_protected_phrases.py

@@ -33,9 +33,11 @@ from python.ebook_search.protected_phrases.matching import (
     detect_protected_phrases_for_query,
     index_chunk_phrase_mentions,
     load_phrase_lookup,
+    phrase_hits_for_chunks,
     resolve_overlaps,
 )
 from python.ebook_search.protected_phrases.models import (
+    ChunkPhraseHit,
     LLMJudgment,
     PhraseCandidate,
     PhraseMatch,
@@ -353,6 +355,9 @@ async def test_index_chunk_phrase_mentions_uses_normalized_window_lookup(
     assert mention.chunk_id == chunk.id
     assert mention.phrase_id == phrase.id
     assert chunk.text[mention.start_char : mention.end_char] == "lock-in"
+    assert await phrase_hits_for_chunks(session, chunk_ids=[chunk.id], phrase_ids=[phrase.id]) == {
+        chunk.id: (ChunkPhraseHit(phrase_id=phrase.id, phrase_text="lock in", mention_count=1),)
+    }
 
 
 @pytest.mark.usefixtures("worker_pool")