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_agent_progress_updates.py

@@ -2,18 +2,18 @@ from unittest.mock import patch
 
 from app.agent.prompt import prompt_manager
 from app.runtime.config import settings
-from app.schemas.types import MessageChannel
+from app.schemas.types import NotificationChannel
 
 
 def test_progress_prompt_is_independent_from_tool_display_mode() -> None:
     """进度沟通规则不应随工具逐条或汇总展示模式变化。"""
     with patch.object(settings, "AI_AGENT_VERBOSE", False):
         summary_mode_prompt = prompt_manager.get_agent_prompt(
-            channel=MessageChannel.WebAgent.value
+            channel=NotificationChannel.WebAgent.value
         )
     with patch.object(settings, "AI_AGENT_VERBOSE", True):
         verbose_mode_prompt = prompt_manager.get_agent_prompt(
-            channel=MessageChannel.WebAgent.value
+            channel=NotificationChannel.WebAgent.value
         )
 
     assert summary_mode_prompt == verbose_mode_prompt