fix: build with direct embedding

packages/leann-backend-hnsw/leann_backend_hnsw/hnsw_backend.py

@@ -141,6 +141,14 @@ class HNSWSearcher(BaseSearcher):
             raise RuntimeError("Index is pruned but recompute is disabled.")
 
         self._index = faiss.read_index(str(index_file), faiss.IO_FLAG_MMAP, hnsw_config)
+        
+        # Load label mapping
+        label_map_file = self.index_dir / "leann.labels.map"
+        if not label_map_file.exists():
+            raise FileNotFoundError(f"Label map file not found at {label_map_file}")
+        
+        with open(label_map_file, "rb") as f:
+            self.label_map = pickle.load(f)
 
     def search(
         self,