Refactor code structure for improved readability and maintainability

backend/app/services/embedding/bge_m3_embedder.py

@@ -1,4 +1,3 @@
-# src/services/embedding/bge_m3_embedder.py
 """BGE-M3嵌入服务 - Dense+Sparse双路向量生成"""
 
 import numpy as np
@@ -293,4 +292,4 @@ def embed_single_text(
 ) -> Dict:
     """便捷函数：对单个文本生成嵌入"""
     embedder = BGEM3Embedder(model_name=model_name, **kwargs)
-    return embedder.embed_single(text)
+    return embedder.embed_single(text)