Release v1.4.16 with crash prevention and hang protection

- Add 30s fetch timeouts to ALL API calls (Real-Debrid, BestDebrid, AllDebrid, Mega-Web)
- Fix race condition in concurrent worker indexing (runWithConcurrency)
- Guard JSON.parse in RealDebrid response with try-catch
- Add try-catch to fs.mkdirSync in download pipeline (handles permission denied)
- Convert MD5/SHA1 hashing to streaming (prevents OOM on large files)
- Add error handling for hash manifest file reading
- Prevent infinite hangs on unresponsive API endpoints

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

src/main/download-manager.ts

@@ -1851,7 +1851,11 @@ export class DownloadManager extends EventEmitter {
         item.provider = unrestricted.provider;
         item.retries += unrestricted.retriesUsed;
         item.fileName = sanitizeFilename(unrestricted.fileName || filenameFromUrl(item.url));
-        fs.mkdirSync(pkg.outputDir, { recursive: true });
+        try {
+          fs.mkdirSync(pkg.outputDir, { recursive: true });
+        } catch (mkdirError) {
+          throw new Error(`Zielordner kann nicht erstellt werden: ${compactErrorText(mkdirError)}`);
+        }
         const existingTargetPath = String(item.targetPath || "").trim();
         const canReuseExistingTarget = existingTargetPath
           && isPathInsideDir(existingTargetPath, pkg.outputDir)