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/auth_repository.ts

@@ -26,7 +26,7 @@ import { RefreshTokenResponse } from "@/data/dto/auth/refresh_token_response";
 import { RegisterRequest } from "@/data/dto/auth/register_request";
 import { SendCodeRequest } from "@/data/dto/auth/send_code_request";
 import { User } from "@/data/dto/user/user";
-import { Result } from "@/data/result";
+import { Result } from "@/utils/result";
 import { AuthStorage } from "@/data/storage/auth/auth_storage";
 import type { IAuthStorage } from "@/data/storage/auth/iauth_storage";
 import { UserStorage } from "@/data/storage/user/user_storage";
@@ -204,10 +204,10 @@ export class AuthRepository {
    */
   async refreshToken(): Promise<Result<RefreshTokenResponse>> {
     const existing = await this.storage.getRefreshToken();
-    if (existing.kind !== "success" || !existing.value) {
+    if (!existing.success || !existing.data) {
       return Result.err(new Error("No refresh token available"));
     }
-    const refreshToken = existing.value;
+    const refreshToken = existing.data;
     return Result.wrap(async () => {
       const response = await this.api.refreshToken(
         RefreshTokenRequest.from({ refreshToken }),
@@ -228,7 +228,7 @@ export class AuthRepository {
     return Result.wrap(async () => {
       const user = await this.api.getCurrentUser();
       const writeResult = await this.userStorage.setUser(user.toJson());
-      if (writeResult.kind === "failure") {
+      if (!writeResult.success) {
         console.warn(
           "[AuthRepository] failed to cache current user",
           writeResult.error,
@@ -261,21 +261,21 @@ export class AuthRepository {
    */
   private async _saveLoginData(data: LoginResponse): Promise<void> {
     const r1 = await this.storage.setLoginToken(data.token);
-    if (r1.kind === "failure") {
+    if (!r1.success) {
       console.warn("[AuthRepository] setLoginToken failed", r1.error);
     }
     if (data.refreshToken) {
       const r2 = await this.storage.setRefreshToken(data.refreshToken);
-      if (r2.kind === "failure") {
+      if (!r2.success) {
         console.warn("[AuthRepository] setRefreshToken failed", r2.error);
       }
     }
     const r3 = await this.userStorage.setUser(data.user.toJson());
-    if (r3.kind === "failure") {
+    if (!r3.success) {
       console.warn("[AuthRepository] setUser failed", r3.error);
     }
     const r4 = await this.userStorage.setUserId(data.user.id);
-    if (r4.kind === "failure") {
+    if (!r4.success) {
       console.warn("[AuthRepository] setUserId failed", r4.error);
     }
   }