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/plugin_system/apis/chat_api.py

@@ -48,9 +48,10 @@ class ChatManager:
             raise TypeError("platform 必须是字符串或是 SpecialTypes 枚举")
         streams = []
         try:
-            for stream in get_chat_manager().streams.values():
-                if platform == SpecialTypes.ALL_PLATFORMS or stream.platform == platform:
-                    streams.append(stream)
+            streams.extend(
+                stream for stream in get_chat_manager().streams.values()
+                if platform == SpecialTypes.ALL_PLATFORMS or stream.platform == platform
+            )
             logger.debug(f"[ChatAPI] 获取到 {len(streams)} 个 {platform} 平台的聊天流")
         except Exception as e:
             logger.error(f"[ChatAPI] 获取聊天流失败: {e}")
@@ -71,9 +72,10 @@ class ChatManager:
             raise TypeError("platform 必须是字符串或是 SpecialTypes 枚举")
         streams = []
         try:
-            for stream in get_chat_manager().streams.values():
-                if (platform == SpecialTypes.ALL_PLATFORMS or stream.platform == platform) and stream.group_info:
-                    streams.append(stream)
+            streams.extend(
+                stream for stream in get_chat_manager().streams.values()
+                if (platform == SpecialTypes.ALL_PLATFORMS or stream.platform == platform) and stream.group_info
+            )
             logger.debug(f"[ChatAPI] 获取到 {len(streams)} 个 {platform} 平台的群聊流")
         except Exception as e:
             logger.error(f"[ChatAPI] 获取群聊流失败: {e}")
@@ -97,9 +99,10 @@ class ChatManager:
             raise TypeError("platform 必须是字符串或是 SpecialTypes 枚举")
         streams = []
         try:
-            for stream in get_chat_manager().streams.values():
-                if (platform == SpecialTypes.ALL_PLATFORMS or stream.platform == platform) and not stream.group_info:
-                    streams.append(stream)
+            streams.extend(
+                stream for stream in get_chat_manager().streams.values()
+                if (platform == SpecialTypes.ALL_PLATFORMS or stream.platform == platform) and not stream.group_info
+            )
             logger.debug(f"[ChatAPI] 获取到 {len(streams)} 个 {platform} 平台的私聊流")
         except Exception as e:
             logger.error(f"[ChatAPI] 获取私聊流失败: {e}")