chat-hook: fix ota chat backlog duplication
=/ old-mailbox=mailbox
(need (scry:cc (unit mailbox) %chat-store [%mailbox chat]))
=* enves envelopes.old-mailbox
- :~ (chat-poke:cc [%delete chat])
+ :~ (chat-poke:cc [%delete new-chat])
+ (chat-poke:cc [%delete chat])
(chat-poke:cc [%create new-chat])
(chat-poke:cc [%messages new-chat enves])
(chat-poke:cc [%read new-chat])
