Refactor sessions to frequently rotate

In order to minimise the window of opportunity to steal a session,
automatically rotate it onto a new session on a frequent basis.  This
makes a session cookie older than the automatic rollover time less
likely to grant access and more likely to be detected.

Should a stolen session cookie get rotated while the attacker is using
it, the user will be notificed that their session has been taken the
next time they open the app if the user re-visits the website before the
session is discarded.

server/api/admin/database-import.post.ts

@@ -40,7 +40,7 @@ export default defineEventHandler(async (event) => {
 		// Only keep sessions that match the account id in both sets to avoid
 		// resurrecting deleted sessions. This will still cause session cross
 		// pollution if a snapshot from another instance is loaded here.
-		return current && current.account.id === session.account.id;
+		return current?.accountId !== undefined && current.accountId === session.accountId;
 	}));
 	await writeSubscriptions(snapshot.subscriptions);
 	await writeSchedule(snapshot.schedule);