Following review feedback on !35 (password generator), secrets are currently held in regular QByteArray/QString without explicit memory wiping after use. \`ksecretd\` is migrating to Botan (kwallet MR !148: https://invent.kde.org/frameworks/kwallet/-/merge_requests/148), which could be a good reference/dependency for KeepSecret to adopt similar secure memory handling. This affects the whole secret-handling pipeline (SecretItemProxy, CollectionModel, ImportExportManager), not just the password generator. So, tracked separately from !35.