revert: remove the batch completion summary

Remove the dedicated completion toast and failure action after user review while leaving all other update and queue improvements intact.

main.js

@@ -2082,7 +2082,6 @@ ipcMain.handle('start-upload', async (_event, payload) => {
       succeeded: 0,
       failed: 0,
       skipped: 0,
-      durationSec: 0,
       files: []
     }, skippedJobs);
     try { await configStore.appendHistory(skippedSummary); } catch (error) {
@@ -2348,8 +2347,6 @@ ipcMain.handle('start-upload', async (_event, payload) => {
         total: tasks.length,
         succeeded: 0,
         failed: tasks.length,
-        skipped: 0,
-        durationSec: 0,
         files: [],
         error: err ? err.message : 'Unbekannter Fehler'
       };