fix: wait for renderer ready before sending tab data

- Wait for did-finish-load event in transfer-tab-data handler
- Await transferTabData before closing file in handlePopOut
- Remove arbitrary 500ms timeout, now uses proper IPC ack flow

src/pages/NoteBrowser.tsx

@@ -135,9 +135,7 @@ export const NoteBrowser = () => {
     const result = await window.electronAPI?.createWindow({ route, title: file.name })
 
     if (result?.success && result.windowId) {
-      setTimeout(() => {
-        window.electronAPI?.transferTabData(result.windowId!, tabData)
-      }, 500)
+      await window.electronAPI?.transferTabData(result.windowId!, tabData)
     }
 
     closeFile(file)