Disk space pre-check, nested extraction, lower I/O priority for hybrid extraction

- Add disk space check before extraction (aborts if insufficient space)
- Add single-level nested archive extraction (archives inside archives)
- Blacklist .iso/.img/.bin/.dmg from nested extraction
- Set real Windows I/O priority (Very Low) on UnRAR via NtSetInformationProcess
- Reduce UnRAR threads to -mt1 during hybrid extraction
- Fix double episode renaming (s01e01e02 pattern)

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

src/main/download-manager.ts

@@ -5128,6 +5128,7 @@ export class DownloadManager extends EventEmitter {
         onlyArchives: readyArchives,
         skipPostCleanup: true,
         packageId,
+        hybridMode: true,
         onProgress: (progress) => {
           if (progress.phase === "done") {
             return;