Cover starting a node whose persisted port (persist_path + "_port.txt")
is already bound by another node, as happens when an application is
restarted while the previous instance still holds the socket. The node
is expected to start on a fallback port instead of failing.
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Add testImportPermanentValueExpires to verify that values originally
stored as permanent (with time_point::max() expiration) properly expire
after being exported and re-imported, since the permanent flag is lost
during the import process.