refactor(data): move dto and schemas out of services directory

src/data/dto/chat/chat_message.ts

@@ -0,0 +1,33 @@
+/**
+ * 聊天历史中的单条消息 DTO
+ */
+import {
+  ChatMessageSchema,
+  type ChatMessageInput,
+  type ChatMessageData,
+} from "@/data/schemas/chat/chat_message";
+
+export class ChatMessage {
+  declare readonly role: string;
+  declare readonly content: string;
+  declare readonly id: string;
+  declare readonly createdAt: string;
+
+  private constructor(input: ChatMessageInput) {
+    const data = ChatMessageSchema.parse(input);
+    Object.assign(this, data);
+    Object.freeze(this);
+  }
+
+  static from(input: ChatMessageInput): ChatMessage {
+    return new ChatMessage(input);
+  }
+
+  static fromJson(json: unknown): ChatMessage {
+    return ChatMessage.from(json as ChatMessageInput);
+  }
+
+  toJson(): ChatMessageData {
+    return ChatMessageSchema.parse(this);
+  }
+}