refactor(data): move Result utility to utils and simplify API

Relocate the Result type from `@/data/result` to `@/utils/result` and
replace the discriminated-union API (`kind`/`value`) with a simpler
boolean-based API (`success`/`data`) across all repositories and
storage classes for improved readability and consistency.

src/data/repositories/chat_repository.ts

@@ -20,7 +20,7 @@ import { ChatHistoryResponse } from "@/data/dto/chat/chat_history_response";
 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 "@/data/result";
+import { Result } from "@/utils/result";
 import { LocalChatStorage } from "@/data/storage/chat/local_chat_storage";
 import { LocalMessage } from "@/data/storage/chat/local_message";
 
@@ -72,7 +72,7 @@ export class ChatRepository {
     messages: readonly ChatMessage[],
   ): Promise<Result<void>> {
     const cleared = await this.localStorage.clearAll();
-    if (cleared.kind === "failure") {
+    if (!cleared.success) {
       return Result.err(cleared.error);
     }
     return this._mapLocalStorageResult(
@@ -83,10 +83,10 @@ export class ChatRepository {
   /** 读取所有本地消息，按 dbId 升序。 */
   async getLocalMessages(): Promise<Result<ChatMessage[]>> {
     const result = await this.localStorage.getAllMessages();
-    if (result.kind === "failure") {
+    if (!result.success) {
       return Result.err(result.error);
     }
-    return Result.ok(result.value.map((lm) => this._localToChat(lm)));
+    return Result.ok(result.data.map((lm) => this._localToChat(lm)));
   }
 
   /** 清空本地消息。 */
@@ -126,20 +126,14 @@ export class ChatRepository {
   }
 
   /**
-   * 把 storage 层 `{kind, value/error}` 形态的 `Result<T>` 桥接到仓库层
-   * `{success, data/error}` 形态。错误统一用 `Error` 包装。
+   * 把 storage 层 `Result<T>` 透传：仓库与 storage 现在共享同一全局
+   * `Result<T>`（来自 `@/utils/result`），不需要任何形状转换。
+   * 该方法保留仅为未来万一又出现差异化时方便快速插入适配。
    */
   private async _mapLocalStorageResult<T>(
-    promise: Promise<
-      | { readonly kind: "success"; readonly value: T }
-      | { readonly kind: "failure"; readonly error: unknown }
-    >,
+    promise: Promise<Result<T>>,
   ): Promise<Result<T>> {
-    const r = await promise;
-    if (r.kind === "success") {
-      return Result.ok(r.value);
-    }
-    return Result.err(r.error);
+    return await promise;
   }
 }