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

tests/test_transfer_message.py

@@ -5,7 +5,7 @@ from app.domain.context import MediaInfo
 from app.domain.meta.metabase import MetaBase
 from app.schemas import TransferInfo
 from app.schemas.tmdb import TmdbEpisode
-from app.schemas.types import ContentType, MediaType, NotificationType
+from app.schemas.types import ContentType, MediaType, MessageType
 
 
 def test_send_transfer_message_passes_episode_info_to_template_context() -> None:
@@ -41,7 +41,7 @@ def test_send_transfer_message_passes_episode_info_to_template_context() -> None
         )
 
     message = post_message.call_args.args[0]
-    assert message.mtype == NotificationType.Organize
+    assert message.mtype == MessageType.Organize
     assert message.ctype == ContentType.OrganizeSuccess
     assert post_message.call_args.kwargs["episodes_info"] is episodes_info
     assert post_message.call_args.kwargs["season_episode"] == "S01 E01"