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_feishu_media_message.py

@@ -8,7 +8,7 @@ ensure_optional_stub("Pinyin2Hanzi", is_pinyin=lambda value: False)
 
 from app.domain.context import MediaInfo
 from app.modules.feishu.feishu import Feishu
-from app.schemas import Notification
+from app.schemas import Message
 
 
 def _build_feishu_client() -> Feishu:
@@ -39,7 +39,7 @@ def test_send_medias_message_passes_first_available_image() -> None:
         return_value={"success": True},
     ) as send_notification:
         result = client.send_medias_message(
-            message=Notification(title="搜索结果", userid="ou_test"),
+            message=Message(title="搜索结果", userid="ou_test"),
             medias=[first_media, second_media],
         )