#10: deleting the last message showed "No messages yet" in the chat list.
The sidebar sent an empty last_body for a deleted (content-cleared) row; now
it sends a last_deleted flag and the row renders "This message was deleted"
(or "You deleted this message"), matching the in-thread placeholder.
#18: added "Delete for me" alongside "Delete for everyone". A new message_hidden
table records a per-user hide; the thread + sidebar (last message, unread) filter
out the requesting user's hidden messages, and the hide is echoed to their other
devices (chat-hidden). "Delete for me" is offered on any message; "Delete for
everyone" stays sender-only.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Sravan
e359271157
