src/preload + src/renderer: contextBridge + React 19 popover/settings

preload/index.ts: window.api 노출 (dirs/watcher/undo/settings/events/app).
renderer/popover: 트레이 팝오버 (300×400, frameless, alwaysOnTop, blur시 자동 닫힘).
renderer/settings: 설정창 (720×560, 3탭: 디렉토리/Undo기록/일반).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/renderer/settings/main.tsx

@@ -0,0 +1,10 @@
+import React from 'react';
+import ReactDOM from 'react-dom/client';
+import { Settings } from './Settings';
+import '../styles.css';
+
+ReactDOM.createRoot(document.getElementById('root')!).render(
+  <React.StrictMode>
+    <Settings />
+  </React.StrictMode>
+);