refactor(schemas): 统一 message/notification 命名边界，旧名收敛至兼容映射表

- notification 域：渠道能力（MessageChannel→NotificationChannel、ChannelCapability* 迁入 notification.py）
- message 域：消息收发（Notification→Message、NotificationType→MessageType、CommingMessage→IncomingMessage、NotificationHistoryItem→MessageHistoryItem、NotificationClear*→MessageClear*）
- Agent 工具契约：send_notification_message→send_message、notification_callback→message_callback
- 源码不保留旧名物理别名，旧导入经 app/runtime/compat/manifest.py SYMBOL_ALIASES 惰性解析
- API 路径与持久化键冻结不变，前端零改动
- 新增兼容守护测试与 docs/rules/07 命名边界规范

app/runtime/extensions/module_manager.py

@@ -5,7 +5,7 @@ from app.runtime.config import settings
 from app.runtime.events import EventHandlerBinding, eventmanager
 from app.foundation.reflection import ModuleHelper
 from app.runtime.log import logger
-from app.schemas.types import EventType, ModuleType, DownloaderType, MediaServerType, MessageChannel, StorageSchema, \
+from app.schemas.types import EventType, ModuleType, DownloaderType, MediaServerType, NotificationChannel, StorageSchema, \
     OtherModulesType, MediaRecognizeType
 from app.foundation.reflection import ObjectUtils
 from app.foundation.singleton import Singleton
@@ -20,7 +20,7 @@ class ModuleManager(metaclass=Singleton):
     SubType = Union[
         DownloaderType,
         MediaServerType,
-        MessageChannel,
+        NotificationChannel,
         StorageSchema,
         OtherModulesType,
         MediaRecognizeType,