refactor(dto): move app models into dto layer

src/stores/chat/chat-machine.actors.ts

@@ -308,4 +308,4 @@ export const sendMessageWsActor = fromPromise<void, { content: string }>(
 );
 
 // Re-export `UiMessage` type for the chat-machine.ts public API
-type UiMessage = import("@/models/chat/ui-message").UiMessage;
+type UiMessage = import("@/data/dto/chat").UiMessage;

src/stores/chat/chat-machine.helpers.ts

@@ -20,7 +20,7 @@
  *   - `AuthStorage` import 已删（只 `readInitData` 用过，移到 `chatInit` actor 上层调用）
  */
 
-import type { UiMessage } from "@/models/chat/ui-message";
+import type { UiMessage } from "@/data/dto/chat";
 import { chatRepository } from "@/data/repositories/chat_repository";
 import type { IChatRepository } from "@/data/repositories/interfaces";
 import { ChatStorage } from "@/data/storage/chat/chat_storage";

src/stores/chat/chat-state.ts

@@ -9,7 +9,7 @@
  *   - `ChatWebSocketConnected` 事件 → true
  *   - `userSession.exit` → false（WS actor cleanup 时也会跑 exit）
  */
-import type { UiMessage } from "@/models/chat/ui-message";
+import type { UiMessage } from "@/data/dto/chat";
 
 export interface ChatState {
   messages: UiMessage[];