变更项目架构，提高扩展性

backend/services/llm_service.py

@@ -0,0 +1,30 @@
+import dashscope
+from http import HTTPStatus
+from backend.core.config import settings
+
+class LLMService:
+    """
+    LLM 服务封装层
+    负责与 DashScope 或其他模型供应商交互
+    """
+    def __init__(self):
+        dashscope.api_key = settings.DASHSCOPE_API_KEY
+    
+    def get_embedding(self, text: str, dimension: int = 1536):
+        """生成文本向量"""
+        try:
+            resp = dashscope.TextEmbedding.call(
+                model=dashscope.TextEmbedding.Models.text_embedding_v4, 
+                input=text,
+                dimension=dimension
+            )
+            if resp.status_code == HTTPStatus.OK:
+                return resp.output['embeddings'][0]['embedding']
+            else:
+                print(f"[ERROR] Embedding API Error: {resp}")
+                return None
+        except Exception as e:
+            print(f"[ERROR] Embedding Exception: {e}")
+            return None
+
+llm_service = LLMService()