添加Ai 能力，重构项目结构

app/ai/models.py

@@ -0,0 +1,64 @@
+"""LLM 模型枚举与实例获取。
+
+Usage:
+    from app.ai.models import LLM
+
+    llm = LLM.DOUBAO_SEED_LITE.create(temperature=0)
+    llm = LLM.CLAUDE_OPUS.create(temperature=0)
+"""
+
+from enum import Enum
+from typing import Callable
+
+from langchain_anthropic import ChatAnthropic
+from langchain_core.language_models import BaseChatModel
+from langchain_openai import ChatOpenAI
+
+from app.config import settings
+
+ConfigGetter = Callable[[], str]
+
+# 供应商连接配置 = (api_key函数, base_url函数)
+_VOLCENGINE = (
+    lambda: settings.volcengine_api_key,
+    lambda: settings.volcengine_base_url,
+)
+_ANTHROPIC = (
+    lambda: settings.anthropic_api_key,
+    lambda: settings.anthropic_base_url,
+)
+
+
+class LLM(Enum):
+    """所有可用模型，每个枚举值 = (模型名, 封装类, api_key函数, base_url函数)。"""
+
+    # 火山引擎（OpenAI 兼容）
+    DOUBAO_PRO_32K = ("doubao-1-5-pro-32k-250115", ChatOpenAI, *_VOLCENGINE)
+    DOUBAO_LITE_32K = ("doubao-1-5-lite-32k-250115", ChatOpenAI, *_VOLCENGINE)
+    DOUBAO_SEED_LITE = ("doubao-seed-2-0-lite-260215", ChatOpenAI, *_VOLCENGINE)
+    DOUBAO_SEED_PRO = ("doubao-seed-2-0-pro-260215", ChatOpenAI, *_VOLCENGINE)
+    DEEPSEEK_V4_FLASH = ("deepseek-v4-flash-260425", ChatOpenAI, *_VOLCENGINE)
+
+    # Claude（Anthropic 风格）
+    CLAUDE_OPUS = ("claude-opus-4-6", ChatAnthropic, *_ANTHROPIC)
+
+    def __init__(
+        self,
+        model_name: str,
+        model_class: type[BaseChatModel],
+        api_key_getter: ConfigGetter,
+        base_url_getter: ConfigGetter,
+    ) -> None:
+        self.model_name = model_name
+        self._model_class = model_class
+        self._api_key_getter = api_key_getter
+        self._base_url_getter = base_url_getter
+
+    def create(self, **kwargs) -> BaseChatModel:
+        """创建模型实例，其他参数透传给 LangChain 模型类。"""
+        return self._model_class(
+            model=self.model_name,
+            api_key=self._api_key_getter(),
+            base_url=self._base_url_getter(),
+            **kwargs,
+        )