refactor(backend): update handlers, utilities and core modules after models restructure

src/api/handlers/base/chat_handler_base.py

@@ -263,7 +263,10 @@ class ChatHandlerBase(BaseMessageHandler, ABC):
         mapping = await mapper.get_mapping(source_model, provider_id)
 
         if mapping and mapping.model:
-            mapped_name = str(mapping.model.provider_model_name)
+            # 使用 select_provider_model_name 支持别名功能
+            # 传入 api_key.id 作为 affinity_key，实现相同用户稳定选择同一别名
+            affinity_key = self.api_key.id if self.api_key else None
+            mapped_name = mapping.model.select_provider_model_name(affinity_key)
             logger.debug(f"[Chat] 模型映射: {source_model} -> {mapped_name}")
             return mapped_name