Start games automatically

[glbert-does]

look into using https://lichess.org/api#tag/Bulk-pairings/operation/bulkPairingCreate to create games and start clocks.

here is how i personally currently imagine it:

• once a game is scheduled, both players need to confirm that it was scheduled correctly, maybe via a button on the site, or via chesster. maybe chesster should send a site link. if either player doesn't, they will have to still start the game manually.
• if a game is rescheduled, players need to confirm again.
• game starts a couple of minutes before or at the scheduled time, clock starts at the scheduled time or a couple of minutes later, definitely a couple of minutes after the game was created. both creating the game at the scheduled time and starting clocks at the scheduled time make some sense to me.
• bulk pairings should create all the games that are supposed to start at a specified time. need to handle errors, especially when a token is not working, which makes all pairings fail according to the documentation.
• can even set "noClaimWin", which would enforce one of our rules.
• need to be careful about players creating their own challenge; definitely cannot create a game when the players already started one themselves, so would have to check for that first.

all of this is very low priority of course. but it would be quite fancy if we had something like this.