feat(model): expose a thread's replies as child rows

setThreadMessages drops the depth-0 message: it is the thread's first message
and the root row already stands for it. Keeping it would show a thread of seven
as one root and seven children, contradicting the reply count the row
advertises. Calling again replaces rather than appends, so a thread reloaded
after a sync does not list its replies twice.

A message row reports its own sender and subject, not the thread's. That is the
mistake worth guarding: the thread's author summary usually contains the first
sender too, so reading it renders something plausible for the root's own reply
and wrong for every other one. Mutation-checked, and the wrong version returns
'Alice' where 'Bob' belongs.

Child rows carry no tag pills. The strip is a row-wide band of the thread's
tags; one under each reply would stripe the list and repeat identical tags down
the expansion.

0 files changed, 0 insertions, 0 deletions