Subscribe to chats about fishauctions HOT 1 CLOSED

to userdata, we need a preference "Email me about new chat replies", along with a help_text that says "unchecking this box will also turn off notifications from N lots", and update the preferences view accordingly

to email_unseen_chats, we need to add a filter to find all ChatSubscription where lot__lothistory__changed_price=False and lot__lot_history__timestamp__gte=F("last_notification_sent"), then email the user about them and update last_notification_sent. Have a link to preferences to turn this off

We also need a new HTMX view that handles turning these subscriptions off (unsubscribed = True) when a user unchecks the checkbox. If the user has turned off "email me about new chat replies", this view can only disable replies. And an update on the lot view to call this when sending a message.

from fishauctions.