feat: complete evidence restructuring worktree

harness/tht/search/__init__.py

@@ -1,6 +1,19 @@
+from typing import Protocol
+
 from pydantic import BaseModel
 
-from tht.vectorstore.store import VectorStore
+from tht.vectorstore.store import VectorHit
+
+
+class SemanticSearcher(Protocol):
+    def search(
+        self,
+        embedding: list[float],
+        *,
+        top_n: int,
+        kinds: list[str] | None,
+        query_text: str | None = None,
+    ) -> list[VectorHit]: ...
 
 
 class SearchResult(BaseModel):
@@ -92,7 +105,7 @@ def combined_search(
     keyword: str,
     *,
     lsh_hits: list[tuple[str, str, str, float]] | None,
-    store: VectorStore,
+    store: SemanticSearcher,
     embedder,
     top: int,
     rrf_k: int,