Add persistent all-time download counter, session vs total stats

- Track totalDownloadedAllTime in settings (persists across restarts)
- Track sessionDownloadedBytes for current app session
- Status bar shows both: Session + Gesamt
- Statistics section shows Heruntergeladen (Session) + (Gesamt)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/main/constants.ts

@@ -76,6 +76,7 @@ export function defaultSettings(): AppSettings {
     collapseNewPackages: true,
     autoSkipExtracted: false,
     confirmDeleteSelection: true,
+    totalDownloadedAllTime: 0,
     bandwidthSchedules: []
   };
 }

src/main/download-manager.ts

@@ -728,6 +728,8 @@ export class DownloadManager extends EventEmitter {
 
   private speedBytesLastWindow = 0;
 
+  private sessionDownloadedBytes = 0;
+
   private statsCache: DownloadStats | null = null;
 
   private statsCacheAt = 0;
@@ -911,6 +913,7 @@ export class DownloadManager extends EventEmitter {
 
     const stats = {
       totalDownloaded,
+      totalDownloadedAllTime: this.settings.totalDownloadedAllTime,
       totalFiles,
       totalPackages: this.session.packageOrder.length,
       sessionStartedAt: this.session.runStartedAt
@@ -4264,6 +4267,8 @@ export class DownloadManager extends EventEmitter {
               written += buffer.length;
               windowBytes += buffer.length;
               this.session.totalDownloadedBytes += buffer.length;
+              this.sessionDownloadedBytes += buffer.length;
+              this.settings.totalDownloadedAllTime += buffer.length;
               this.itemContributedBytes.set(active.itemId, (this.itemContributedBytes.get(active.itemId) || 0) + buffer.length);
               this.recordSpeed(buffer.length, item.packageId);
               throughputWindowBytes += buffer.length;

src/main/storage.ts

@@ -109,6 +109,7 @@ export function normalizeSettings(settings: AppSettings): AppSettings {
     collapseNewPackages: settings.collapseNewPackages !== undefined ? Boolean(settings.collapseNewPackages) : defaults.collapseNewPackages,
     autoSkipExtracted: settings.autoSkipExtracted !== undefined ? Boolean(settings.autoSkipExtracted) : defaults.autoSkipExtracted,
     confirmDeleteSelection: settings.confirmDeleteSelection !== undefined ? Boolean(settings.confirmDeleteSelection) : defaults.confirmDeleteSelection,
+    totalDownloadedAllTime: typeof settings.totalDownloadedAllTime === "number" && settings.totalDownloadedAllTime >= 0 ? settings.totalDownloadedAllTime : defaults.totalDownloadedAllTime,
     theme: VALID_THEMES.has(settings.theme) ? settings.theme : defaults.theme,
     bandwidthSchedules: normalizeBandwidthSchedules(settings.bandwidthSchedules)
   };