Show the latest timestamp in chifra status

[tjayrush]

chifra export depends on the timestamps file being up to date. It used to be the case that we would install the timestamps file on first install and then expect the user to run chifra scrape so that chifra export would report up to the head of the chain. With the new chifra init, where we're expecting now to download the timestamp file, it makes sense that the latest timestamp is shown in the status.

Change the last line to say Progress: xxx (latest), xxx (finalized), yyy (staged), zzz (unripe), ttt (timestamps)

Although, obviously, finalized is now a terrible word.