feat: add ApiError class to preserve error data through unwrapApiBody

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

app/utils/http/factory.ts

@@ -7,13 +7,20 @@ export type ApiResponse<T = unknown> = {
     data: T
 }
 
+/** Wraps API error responses, preserving the data field for field-level error handling */
+export class ApiError extends Error {
+    constructor(message: string, public data: unknown) {
+        super(message)
+        this.name = 'ApiError'
+    }
+}
 
 /** 从 Nitro 推断的响应体上剥离一层 `ApiResponse`，得到 `data` 字段类型 */
 export type UnwrapApiResponse<T> = T extends ApiResponse<infer D> ? D : T
 
 export function unwrapApiBody<T>(payload: ApiResponse<T>): T {
     if (payload.code !== 0) {
-        throw new Error(payload.message)
+        throw new ApiError(payload.message, payload.data)
     }
     return payload.data
 }