fix(adminfront): fix double-click required for file input in bulk upload modal

Refactored the file input button to use a native HTML label with Radix UI's asChild prop. This ensures the file dialog opens reliably on the first click without relying on JS synthetic click events.

adminfront/src/features/users/components/UserBulkUploadModal.tsx

@@ -416,20 +416,23 @@ export function UserBulkUploadModal({
                     "템플릿 다운로드",
                   )}
                 </Button>
-                <input
-                  type="file"
-                  accept=".csv"
-                  className="hidden"
-                  ref={fileInputRef}
-                  onChange={handleFileChange}
-                />
-                <Button
-                  onClick={() => fileInputRef.current?.click()}
-                  variant="secondary"
-                >
-                  {file
-                    ? t("ui.common.change_file", "파일 변경")
-                    : t("ui.common.select_file", "파일 선택")}
+                <Button asChild variant="secondary" className="cursor-pointer">
+                  <label>
+                    {file
+                      ? t("ui.common.change_file", "파일 변경")
+                      : t("ui.common.select_file", "파일 선택")}
+                    <input
+                      type="file"
+                      accept=".csv"
+                      className="hidden"
+                      ref={fileInputRef}
+                      onChange={handleFileChange}
+                      onClick={(e) => {
+                        // Allow picking the same file again if it was cleared
+                        (e.target as HTMLInputElement).value = "";
+                      }}
+                    />
+                  </label>
                 </Button>
               </div>