refactor(auth): standardize API response structure and remove unused error handling

server/shared/types.ts

@@ -5,15 +5,6 @@ export type ApiSuccessShape<TData = unknown> = {
   data: TData;
 };
 
-export type ApiErrorShape = {
-  success: false;
-  error: {
-    code: string;
-    message: string;
-    details?: unknown;
-  };
-};
-
 // ---------------------------------------------------------------------------------------------
 
 export type LLMProvider = 'claude' | 'codex' | 'gemini' | 'cursor';

server/shared/utils.ts

@@ -6,7 +6,6 @@ import path from 'node:path';
 import type { NextFunction, Request, RequestHandler, Response } from 'express';
 
 import type {
-  ApiErrorShape,
   ApiSuccessShape,
   AppErrorOptions,
   NormalizedMessage,
@@ -30,21 +29,6 @@ export function createApiSuccessResponse<TData>(
   };
 }
 
-export function createApiErrorResponse(
-  code: string,
-  message: string,
-  details?: unknown
-): ApiErrorShape {
-  return {
-    success: false,
-    error: {
-      code,
-      message,
-      details,
-    }
-  };
-}
-
 export function asyncHandler(
   handler: (req: Request, res: Response, next: NextFunction) => Promise<unknown>
 ): RequestHandler {