[feat]: Item Master 데이터 관리 기능 구현 및 타입 에러 수정

- ItemMasterDataManagement 컴포넌트 구조화 (tabs, dialogs, components 분리)
- HierarchyTab 타입 에러 수정 (BOMItem section_id, updated_at 추가)
- API 클라이언트 구현 (item-master.ts, 13개 엔드포인트)
- ItemMasterContext 구현 (상태 관리 및 데이터 흐름)
- 백엔드 요구사항 문서 작성 (CORS 설정, API 스펙 등)
- SSR 호환성 수정 (navigator API typeof window 체크)
- 미사용 변수 ESLint 에러 해결
- Context 리팩토링 (AuthContext, RootProvider 추가)
- API 유틸리티 추가 (error-handler, logger, transformers)

🤖 Generated with Claude Code

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

src/components/ui/dialog.tsx

@@ -57,7 +57,7 @@ const DialogContent = React.forwardRef<
       ref={ref}
       data-slot="dialog-content"
       className={cn(
-        "bg-background data-[state=open]:animate-in data-[state=closed]:animate-out data-[state=closed]:fade-out-0 data-[state=open]:fade-in-0 data-[state=closed]:zoom-out-95 data-[state=open]:zoom-in-95 fixed top-[50%] left-[50%] z-50 grid w-full max-w-[calc(100%-2rem)] translate-x-[-50%] translate-y-[-50%] gap-4 rounded-lg border p-6 shadow-lg duration-200 sm:max-w-lg",
+        "bg-background data-[state=open]:animate-in data-[state=closed]:animate-out data-[state=closed]:fade-out-0 data-[state=open]:fade-in-0 data-[state=closed]:zoom-out-95 data-[state=open]:zoom-in-95 fixed top-[50%] left-[50%] z-50 grid w-full max-w-[calc(100%-2rem)] translate-x-[-50%] translate-y-[-50%] gap-4 rounded-lg border p-6 shadow-lg duration-200 sm:max-w-lg overflow-hidden",
         className,
       )}
       {...props}

src/components/ui/error-message.tsx

@@ -0,0 +1,38 @@
+// 에러 메시지 컴포넌트
+// API 오류 메시지 일관된 UI로 표시
+
+import React from 'react';
+import { AlertCircle } from 'lucide-react';
+import { Alert, AlertDescription, AlertTitle } from '@/components/ui/alert';
+
+interface ErrorMessageProps {
+  title?: string;
+  message: string;
+  onRetry?: () => void;
+  className?: string;
+}
+
+export const ErrorMessage: React.FC<ErrorMessageProps> = ({
+  title = '오류 발생',
+  message,
+  onRetry,
+  className = ''
+}) => {
+  return (
+    <Alert variant="destructive" className={className}>
+      <AlertCircle className="h-4 w-4" />
+      <AlertTitle>{title}</AlertTitle>
+      <AlertDescription className="mt-2">
+        <p>{message}</p>
+        {onRetry && (
+          <button
+            onClick={onRetry}
+            className="mt-2 text-sm underline hover:no-underline"
+          >
+            다시 시도
+          </button>
+        )}
+      </AlertDescription>
+    </Alert>
+  );
+};

src/components/ui/loading-spinner.tsx

@@ -0,0 +1,29 @@
+// 로딩 스피너 컴포넌트
+// API 호출 중 로딩 상태 표시용
+
+import React from 'react';
+
+interface LoadingSpinnerProps {
+  size?: 'sm' | 'md' | 'lg';
+  className?: string;
+  text?: string;
+}
+
+export const LoadingSpinner: React.FC<LoadingSpinnerProps> = ({
+  size = 'md',
+  className = '',
+  text
+}) => {
+  const sizeClasses = {
+    sm: 'h-4 w-4',
+    md: 'h-8 w-8',
+    lg: 'h-12 w-12'
+  };
+
+  return (
+    <div className={`flex flex-col items-center justify-center gap-2 ${className}`}>
+      <div className={`animate-spin rounded-full border-b-2 border-primary ${sizeClasses[size]}`} />
+      {text && <p className="text-sm text-muted-foreground">{text}</p>}
+    </div>
+  );
+};