Retry failed update recovery

Starts restoration of the retained installation after an update recovery failure. Requires the **admin** role; remains available while licensing or permissions block management. Retained recovery files must still be present.

curl -X POST "https://example.com/api/updates/recover"

{  "id": "string",  "target": "string",  "phase": "preparing",  "error": "string",  "recoveryAvailable": true,  "previousTransactionID": "string"}