Add detailed preparation labels and dash separator for post-process status

- Show "Entpacken vorbereiten..." while scanning archives and checking disk space
- Show "Archive scannen..." and "Speicherplatz prüfen..." phases from extractor
- Use dash separator in UI: "[10/10 - Done] - Entpacken 45% (3/6)"
- Handle new "preparing" phase in both hybrid and full extraction progress handlers

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

src/renderer/App.tsx

@@ -3371,7 +3371,7 @@ const PackageCard = memo(function PackageCard({ pkg, items, packageSpeed, isFirs
                 <span key={col} className={`pkg-col pkg-col-prio${pkg.priority === "high" ? " prio-high" : pkg.priority === "low" ? " prio-low" : ""}`}>{pkg.priority === "high" ? "Hoch" : pkg.priority === "low" ? "Niedrig" : ""}</span>
               );
               case "status": return (
-                <span key={col} className="pkg-col pkg-col-status">[{done}/{total}{done === total && total > 0 ? " - Done" : ""}{failed > 0 ? ` · ${failed} Fehler` : ""}{cancelled > 0 ? ` · ${cancelled} abgebr.` : ""}]{pkg.postProcessLabel ? ` ${pkg.postProcessLabel}` : ""}</span>
+                <span key={col} className="pkg-col pkg-col-status">[{done}/{total}{done === total && total > 0 ? " - Done" : ""}{failed > 0 ? ` · ${failed} Fehler` : ""}{cancelled > 0 ? ` · ${cancelled} abgebr.` : ""}]{pkg.postProcessLabel ? ` - ${pkg.postProcessLabel}` : ""}</span>
               );
               case "speed": return (
                 <span key={col} className="pkg-col pkg-col-speed">{packageSpeed > 0 ? formatSpeedMbps(packageSpeed) : ""}</span>