Add retry extraction context menu, increase error text limit

- Right-click packages with extraction errors shows "Extraktion
  wiederholen" option to manually retry
- Increase WinRAR error text from 240 to 500 chars for better
  diagnostics in logs

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

src/preload/preload.ts

@@ -47,6 +47,7 @@ const api: ElectronApi = {
   exportBackup: (): Promise<{ saved: boolean }> => ipcRenderer.invoke(IPC_CHANNELS.EXPORT_BACKUP),
   importBackup: (): Promise<{ restored: boolean; message: string }> => ipcRenderer.invoke(IPC_CHANNELS.IMPORT_BACKUP),
   openLog: (): Promise<void> => ipcRenderer.invoke(IPC_CHANNELS.OPEN_LOG),
+  retryExtraction: (packageId: string): Promise<void> => ipcRenderer.invoke(IPC_CHANNELS.RETRY_EXTRACTION, packageId),
   onStateUpdate: (callback: (snapshot: UiSnapshot) => void): (() => void) => {
     const listener = (_event: unknown, snapshot: UiSnapshot): void => callback(snapshot);
     ipcRenderer.on(IPC_CHANNELS.STATE_UPDATE, listener);