fix: handle TorBox 'checking' state as downloading, add symlink completion logging

- Add 'checking' to the list of downloading states in getTorboxStatus()
  so TorBox torrents in transitional state don't get marked as error
- Add debug log before calling onSuccess to trace state update flow

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

pkg/debrid/providers/torbox/torbox.go

@@ -187,7 +187,8 @@ func (tb *Torbox) getTorboxStatus(status string, finished bool) string {
 	downloading := []string{"paused", "downloading", "uploading",
 		"checkingResumeData", "metaDL", "pausedUP", "queuedUP", "checkingUP",
 		"forcedUP", "allocating", "downloading", "metaDL", "pausedDL",
-		"queuedDL", "checkingDL", "forcedDL", "checkingResumeData", "moving"}
+		"queuedDL", "checkingDL", "forcedDL", "checkingResumeData", "moving",
+		"checking"}
 
 	var determinedStatus string
 	switch {