파일 이름 변경 내용에 접미사 추가

src/renderer/renderer.js

@@ -27,6 +27,7 @@ const btnSortDate      = document.getElementById('btn-sort-date');
 const btnRename        = document.getElementById('btn-rename');
 const inputPrefix      = document.getElementById('input-prefix');
 const inputDigits      = document.getElementById('input-digits');
+const inputPostfix     = document.getElementById('input-postfix');
 const previewName      = document.getElementById('preview-name');
 const dirPath          = document.getElementById('dir-path');
 const rubberBand       = document.getElementById('rubber-band');
@@ -113,6 +114,7 @@ window.api.onFullscreenChange((isFullscreen) => {
 // ── 버튼 / 키보드 이벤트 ─────────────────────────
 inputPrefix.addEventListener('input', updatePreview);
 inputDigits.addEventListener('input', updatePreview);
+inputPostfix.addEventListener('input', updatePreview);
 btnOpen.addEventListener('click', () => {
   log('ui', 'open button clicked');
   folderController.openFolder();
@@ -146,7 +148,9 @@ initKeyboardShortcuts({
 function updatePreview() {
   const prefix = inputPrefix.value.trim() || 'photo';
   const digits = clampDigits(inputDigits.value);
+  const postfix = inputPostfix.value.trim();
   const ext    = state.files.length ? getExtension(state.files[0].name) : 'jpg';
-  previewName.textContent = `${prefix}_${'1'.padStart(digits, '0')}.${ext}`;
+  const suffix = postfix ? `_${postfix}` : '';
+  previewName.textContent = `${prefix}_${'1'.padStart(digits, '0')}${suffix}.${ext}`;
   updateNewNameLabels();
 }