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/api/endpoints/openai.py

@@ -19,7 +19,7 @@ from app.agent.callback import StreamingHandler
 from app.agent.orchestrator import MoviePilotAgent
 from app.runtime.config import settings
 from app.application.security.access import openai_bearer_scheme
-from app.schemas.types import MessageChannel
+from app.schemas.types import NotificationChannel
 
 OPENAI_ERROR_RESPONSES = {
     400: {"model": schemas.OpenAIErrorResponse, "description": "请求格式错误"},
@@ -341,7 +341,7 @@ async def chat_completions(
     agent = _CollectingMoviePilotAgent(
         session_id=session_id,
         user_id=session_key,
-        channel=MessageChannel.Web.value,
+        channel=NotificationChannel.Web.value,
         source="openai",
         username=username,
         stream_mode=payload.stream,
@@ -434,7 +434,7 @@ async def responses(
     agent = _CollectingMoviePilotAgent(
         session_id=session_id,
         user_id=session_key,
-        channel=MessageChannel.Web.value,
+        channel=NotificationChannel.Web.value,
         source="openai.responses",
         username=str(payload.user or "openai-client"),
         stream_mode=False,