feat(statistics): persist ranges and align history columns

Persist per-day download volume, outcomes, active transfer time, and provider results so today, seven-day, and 30-day views use real partial-window data. Preserve existing all-time counters while extending totals with newly recorded result metrics. Rebuild the history table around one resizable persisted grid shared by headers and rows, with synchronized overflow and consistent alignment across window sizes.

src/main/app-controller.ts

@@ -71,6 +71,7 @@ import type { DebugSetupCheckResult, SupportTraceConfig } from "../shared/types"
 import { createOnlineBackup, downloadOnlineBackup, uploadOnlineBackup } from "./online-backup";
 import { overlayLiveUsageCounters } from "./settings-live-overlay";
 import { getLegacyDesktopLogDirectory, migrateLogDirectories, prepareLogDirectory, resolveLogDirectory } from "./log-storage";
+import { normalizeStatisticsLedger, saveStatisticsLedger } from "./statistics-ledger";
 
 function sanitizeSettingsPatch(partial: Partial<AppSettings>): Partial<AppSettings> {
   const entries = Object.entries(partial || {}).filter(([, value]) => value !== undefined);
@@ -882,7 +883,8 @@ export class AppController {
       appVersion: APP_VERSION,
       exportedAt: new Date().toISOString(),
       session: this.manager.getSession(),
-      history: loadHistoryForRetention(this.storagePaths, this.settings.historyRetentionMode, this.historyLimits()),
+      history: loadHistoryForRetention(this.storagePaths, this.settings.historyRetentionMode, this.historyLimits()),
+      statistics: this.manager.getStats().statistics!,
       remoteDiagnostics
     });
     const encrypted = encryptBackup(JSON.stringify(payloadObj), passphrase);
@@ -1001,7 +1003,11 @@ export class AppController {
     const restoredSession = normalizeLoadedSessionTransientFields(
       normalizeLoadedSession(parsed.session)
     );
-    saveSession(this.storagePaths, restoredSession);
+    saveSession(this.storagePaths, restoredSession);
+
+    if (parsed.statistics) {
+      saveStatisticsLedger(this.storagePaths.statisticsFile, normalizeStatisticsLedger(parsed.statistics));
+    }
 
     if (Array.isArray(parsed.history) && parsed.history.length > 0) {
       const normalizedHistory = (parsed.history as unknown[])