fix(WEB): 견적 등록 제품 선택 목록 React key 오류 수정

- 제품 목록에서 null/undefined item_code 필터링
- 중복 item_code 제거 로직 추가
- key prop에 index 조합으로 고유성 보장

src/components/quotes/QuoteRegistration.tsx

@@ -813,11 +813,16 @@ export function QuoteRegistration({
                         <SelectValue placeholder={isLoadingProducts ? "로딩 중..." : "제품을 선택하세요"} />
                       </SelectTrigger>
                       <SelectContent>
-                        {getFilteredProducts(formData.items[activeItemIndex].productCategory).map((product) => (
-                          <SelectItem key={product.item_code} value={product.item_code}>
-                            {product.item_name} ({product.item_code})
-                          </SelectItem>
-                        ))}
+                        {getFilteredProducts(formData.items[activeItemIndex].productCategory)
+                          .filter((product) => product.item_code) // null/undefined 제외
+                          .filter((product, index, self) =>
+                            index === self.findIndex(p => p.item_code === product.item_code)
+                          )
+                          .map((product, index) => (
+                            <SelectItem key={`${product.item_code}-${index}`} value={product.item_code}>
+                              {product.item_name} ({product.item_code})
+                            </SelectItem>
+                          ))}
                       </SelectContent>
                     </Select>
                   </FormField>