refactor(data): add I*Repository interfaces and depend on them in stores

为 /src/data/repositories/ 下每个仓库类增加对应的接口契约，
接口文件存放在独立的 interfaces/ 子目录中。

改动:
- 新建 4 个接口文件 (iauth_repository / ichat_repository /
  imetrics_repository / iuser_repository)，纯 type-only，方法签名
  与实现类完全一致
- 4 个实现类加 implements I{Name}Repository 子句，编译器自动校验契约
- 3 个 stores 文件 (auth / chat / user state machines) 改为依赖接口
  类型：通过 `const xxxRepo: I{Name}Repository = xxxRepository` 局部别名，
  actor 内部调用全部走别名
- barrelsby.json 加入 interfaces/ 目录，让自动 barrel 能覆盖
- Auto-regenerated repositories/index.ts 与 interfaces/index.ts

参照 storage 层已有的 IAuthStorage / IChatStorage / IUserStorage 模式。

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/data/repositories/chat_repository.ts

@@ -21,10 +21,11 @@ import { ChatMessage } from "@/data/dto/chat/chat_message";
 import { ChatSendResponse } from "@/data/dto/chat/chat_send_response";
 import { SendMessageRequest } from "@/data/dto/chat/send_message_request";
 import { Result } from "@/utils/result";
+import type { IChatRepository } from "@/data/repositories/interfaces/ichat_repository";
 import { LocalChatStorage } from "@/data/storage/chat/local_chat_storage";
 import { LocalMessage } from "@/data/storage/chat/local_message";
 
-export class ChatRepository {
+export class ChatRepository implements IChatRepository {
   constructor(
     private readonly api: ChatApi,
     private readonly localStorage: LocalChatStorage,