refactor: 统一类型注解风格并优化代码结构

- 将裸 except 改为显式 Exception 捕获
- 用列表推导式替换冗余 for 循环
- 为类属性添加 ClassVar 注解
- 统一 Union/Optional 写法为 |
- 移除未使用的导入
- 修复 SQLAlchemy 空值比较语法
- 优化字符串拼接与字典更新逻辑
- 补充缺失的 noqa 注释与异常链

BREAKING CHANGE: 所有插件基类的类级字段现要求显式 ClassVar 注解，自定义插件需同步更新

src/llm_models/model_client/aiohttp_gemini_client.py

@@ -372,10 +372,7 @@ def _default_normal_response_parser(
 
             # 解析文本内容
             if "content" in candidate and "parts" in candidate["content"]:
-                content_parts = []
-                for part in candidate["content"]["parts"]:
-                    if "text" in part:
-                        content_parts.append(part["text"])
+                content_parts = [part["text"] for part in candidate["content"]["parts"] if "text" in part]
 
                 if content_parts:
                     api_response.content = "".join(content_parts)

src/llm_models/model_client/openai_client.py

@@ -3,7 +3,7 @@ import base64
 import io
 import re
 from collections.abc import Callable, Coroutine, Iterable
-from typing import Any
+from typing import Any, ClassVar
 
 import orjson
 from json_repair import repair_json
@@ -376,7 +376,7 @@ def _default_normal_response_parser(
 @client_registry.register_client_class("openai")
 class OpenaiClient(BaseClient):
     # 类级别的全局缓存：所有 OpenaiClient 实例共享
-    _global_client_cache: dict[int, AsyncOpenAI] = {}
+    _global_client_cache: ClassVar[dict[int, AsyncOpenAI] ] = {}
     """全局 AsyncOpenAI 客户端缓存：config_hash -> AsyncOpenAI 实例"""
 
     def __init__(self, api_provider: APIProvider):

src/llm_models/utils_model.py

@@ -534,7 +534,7 @@ class _RequestExecutor:
         model_name = model_info.name
         retry_interval = api_provider.retry_interval
 
-        if isinstance(e, (NetworkConnectionError, ReqAbortException)):
+        if isinstance(e, NetworkConnectionError | ReqAbortException):
             return await self._check_retry(remain_try, retry_interval, "连接异常", model_name)
         elif isinstance(e, RespNotOkException):
             return await self._handle_resp_not_ok(e, model_info, api_provider, remain_try, messages_info)
@@ -1064,7 +1064,8 @@ class LLMRequest:
                 # 遍历工具的参数
                 for param in tool.get("parameters", []):
                     # 严格验证参数格式是否为包含5个元素的元组
-                    assert isinstance(param, tuple) and len(param) == 5, "参数必须是包含5个元素的元组"
+                    assert isinstance(param, tuple), "参数必须是元组"
+                    assert len(param) == 5, "参数必须包含5个元素"
                     builder.add_param(
                         name=param[0],
                         param_type=param[1],