fix(sns): derive per-user totals from timeline counts map

electron/main.ts

@@ -1509,6 +1509,10 @@ function registerIpcHandlers() {
     return snsService.getSnsUsernames()
   })
 
+  ipcMain.handle('sns:getUserPostCounts', async () => {
+    return snsService.getUserPostCounts()
+  })
+
   ipcMain.handle('sns:getExportStats', async () => {
     return snsService.getExportStats()
   })