Account-rotation logging + transient cooldown fixes

- New dedicated account-rotation.log (audit-style) so multi-account/key
  rotation flow is visible without rd_downloader.log noise
- Mega-Debrid: always show "Account X/Y (masked@login)" label even with
  one account, and log a clear "TESTE Account fuer Link-Generierung..."
  line BEFORE every network call so the user sees which account is in
  play even if the call hangs
- Mega-Debrid: on FAILED, log which account will be tried next
  (skipping disabled/limited/cooldown ones), so the rotation is auditable
- Mega-Web "Antwort leer" / empty body now uses 20s cooldown instead of
  120s — empty responses are typically transient server hiccups, not
  real failures (caused healthy accounts to be unfairly blocked)
- Generic transport/unknown errors: 30s cooldown instead of 120s
- Global stall watchdog no longer counts items in "validating" status —
  per-item validating watchdog already handles them and gives the
  multi-account rotation enough time. Without this fix the global
  watchdog could abort the unrestrict mid-rotation (e.g. account 3 of 3
  still being tested) just because no download bytes had arrived
- Same logging treatment applied to Debrid-Link key rotation

src/main/app-controller.ts

@@ -37,6 +37,7 @@ import { abortActiveUpdateDownload, checkGitHubUpdate, installLatestUpdate } fro
 import { rotateDebugToken, startDebugServer, stopDebugServer } from "./debug-server";
 import { encryptBackup, decryptBackup } from "./backup-crypto";
 import { getAuditLogPath, initAuditLog, logAuditEvent, shutdownAuditLog } from "./audit-log";
+import { initAccountRotationLog, shutdownAccountRotationLog } from "./account-rotation-log";
 import { getDebugSetupCheck } from "./debug-setup";
 import { buildLinkExportSelection, serializeLinkExportText } from "./link-export";
 import { getRenameLogPath, initRenameLog, shutdownRenameLog } from "./rename-log";
@@ -84,6 +85,7 @@ export class AppController {
     initPackageLogs(this.storagePaths.baseDir);
     initItemLogs(this.storagePaths.baseDir);
     initAuditLog(this.storagePaths.baseDir);
+    initAccountRotationLog(this.storagePaths.baseDir);
     initRenameLog(this.storagePaths.baseDir);
     initTraceLog(this.storagePaths.baseDir);
     this.settings = loadSettings(this.storagePaths);
@@ -557,21 +559,21 @@ export class AppController {
     return encryptBackup(payload);
   }
 
-  public exportSupportBundle(): { buffer: Buffer; defaultFileName: string } {
-    this.audit("INFO", "Support-Bundle exportiert");
+  public exportSupportBundle(): { buffer: Buffer; defaultFileName: string } {
+    this.audit("INFO", "Support-Bundle exportiert");
     logTraceEvent("INFO", "support", "Support-Bundle erstellt", {
       packageCount: Object.keys(this.manager.getSnapshot().session.packages).length,
       itemCount: Object.keys(this.manager.getSnapshot().session.items).length
     });
-    return {
-      buffer: buildSupportBundle(this.manager, this.storagePaths.baseDir, { hostDiagnosticsMode: "cached" }),
-      defaultFileName: getSupportBundleDefaultFileName()
-    };
-  }
-
-  public getSupportBundleDefaultFileName(): string {
-    return getSupportBundleDefaultFileName();
-  }
+    return {
+      buffer: buildSupportBundle(this.manager, this.storagePaths.baseDir, { hostDiagnosticsMode: "cached" }),
+      defaultFileName: getSupportBundleDefaultFileName()
+    };
+  }
+
+  public getSupportBundleDefaultFileName(): string {
+    return getSupportBundleDefaultFileName();
+  }
 
   public importBackup(data: Buffer): { restored: boolean; message: string } {
     let parsed: Record<string, unknown>;
@@ -679,6 +681,7 @@ export class AppController {
     shutdownRenameLog();
     this.audit("INFO", "App beendet");
     shutdownTraceLog();
+    shutdownAccountRotationLog();
     shutdownAuditLog();
     if (this.settings.historyRetentionMode === "session") {
       clearHistory(this.storagePaths);