fix: add missing rendererReady call and fix temporal dead zone crash

- App.tsx: call electronAPI.file.rendererReady() on mount so main process
  opens pendingFile (files passed via CLI or file associations)
- FindReplaceBar: move updateMatchCount declaration before executeCommand
  to fix 'Cannot access d before initialization' crash in minified build
  (executeCommand referenced updateMatchCount via closure before its
  const declaration in the same scope)

src/renderer/App.tsx

@@ -15,6 +15,10 @@ function App() {
   useAutoUpdateCheck();
   const [printOpen, setPrintOpen] = useState(false);
 
+  useEffect(() => {
+    window.electronAPI?.file?.rendererReady?.();
+  }, []);
+
   useEffect(() => {
     const handler = () => setPrintOpen(true);
     window.addEventListener('mc:print', handler);