Auto-Rename Race-Fix: parallele Scans pro Package serialisieren

Im Production-Log:
  21:30:33.957Z Auto-Rename Scan gestartet | videoFiles=25
  21:30:33.992Z Auto-Rename Scan gestartet | videoFiles=25  (35ms spaeter, gleiches pkg!)
  21:30:33.994Z Auto-Rename durchgefuehrt | E24.B          (Scan 1)
  21:30:34.009Z Auto-Rename uebersprungen: Ziel existiert  (Scan 2 sieht renamed file)
  21:30:34.029Z Auto-Rename durchgefuehrt | E24.A          (Scan 1)
  21:30:34.056Z Auto-Rename fehlgeschlagen | ENOENT        (Scan 2 versucht renamed file)

Ursache: hybrid-extract feuert nach JEDEM erfolgreichen Archive einen
fire-and-forget autoRename (Z.10915), und der deferred Post-Process-Pfad
ruft am Ende nochmal autoRename auf (Z.11630). Bei einem Multi-Archive-
Package (25 Episoden) ueberlappen sich 2+ Scans auf demselben Fileset.

Ergebnis: "Ziel existiert"-Warnungen + ENOENT-Fehler beim Rename.
Manchmal blieben einzelne Files unbenannt durchrutschen (Scan 2 sieht
File X, will renamen, aber Scan 1 hat es schon weg-renamed).

Fix: pro Package via Promise-Chaining serialisieren. Neue Map
autoRenameInFlight haelt das laufende Scan-Promise pro packageId. Der
neue Wrapper kettet jeden weiteren Aufruf an das vorherige Promise an
— so laeuft maximal ein Scan zur Zeit pro Package, der naechste startet
erst wenn der vorherige fertig ist (und sieht damit den korrekten
Disk-State).

Test: zwei parallele autoRenameExtractedVideoFiles-Aufrufe fuer dasselbe
Package mit 3 obfuskierten Files. Beide resolven sauber, Summe der
Renames == 3, alle 3 Folders enthalten am Ende den korrekten Folder-
Namen statt Hoster-Obfuskation. 582/582 Tests gruen.

src/main/download-manager.ts

@@ -1685,6 +1685,18 @@ export class DownloadManager extends EventEmitter {
 
   private itemContributedBytes = new Map<string, number>();
 
+  /** Per-package serialization for autoRenameExtractedVideoFiles. The hybrid-
+   *  extract path fires a fire-and-forget rename after every successful
+   *  archive iteration, and the deferred post-process path runs another
+   *  rename when post-processing finishes. For a multi-archive package
+   *  (e.g. 25 episodes) these can overlap, with two concurrent scans seeing
+   *  the same files, racing to rename, and producing "Ziel existiert" /
+   *  ENOENT noise plus occasionally missed renames. We chain subsequent
+   *  invocations onto the running promise so the second scan re-scans
+   *  AFTER the first finishes — picking up any newly-arrived files while
+   *  guaranteeing no two scans operate on the same fileset simultaneously. */
+  private autoRenameInFlight = new Map<string, Promise<number>>();
+
   private runItemIds = new Set<string>();
 
   private runPackageIds = new Set<string>();
@@ -3661,6 +3673,36 @@ export class DownloadManager extends EventEmitter {
     extractDir: string,
     pkg?: PackageEntry,
     shouldAbort?: () => boolean
+  ): Promise<number> {
+    // Serialize per-package: chain onto any in-flight scan for the same
+    // package so two scans never read the same fileset in parallel. Without
+    // this, hybrid-extract's per-archive trigger + the deferred post-process
+    // trigger frequently overlap and cause "Ziel existiert" / ENOENT
+    // log noise (and occasionally a missed rename when the second scan's
+    // chosen target file disappears between scan and rename).
+    if (!pkg) {
+      return this.autoRenameExtractedVideoFilesImpl(extractDir, undefined, shouldAbort);
+    }
+    const previous = this.autoRenameInFlight.get(pkg.id);
+    const next = (previous ?? Promise.resolve(0)).catch(() => 0).then(() =>
+      this.autoRenameExtractedVideoFilesImpl(extractDir, pkg, shouldAbort)
+    );
+    this.autoRenameInFlight.set(pkg.id, next);
+    try {
+      return await next;
+    } finally {
+      // Only clear the slot if no newer chained call took our place. This
+      // keeps the chain intact when several callers queue up at once.
+      if (this.autoRenameInFlight.get(pkg.id) === next) {
+        this.autoRenameInFlight.delete(pkg.id);
+      }
+    }
+  }
+
+  private async autoRenameExtractedVideoFilesImpl(
+    extractDir: string,
+    pkg?: PackageEntry,
+    shouldAbort?: () => boolean
   ): Promise<number> {
     if (!this.settings.autoRename4sf4sj) {
       return 0;