- Replies: Reply on a message's long press puts it above the composer;
sent replies quote the message they answer (sender and first line),
with the reply fallback left out of the body.
- Reactions: six quick ones and any other on long press, chips under the
message with counts, the user's own highlighted; tapping a chip adds or
takes back a reaction, a long press lists who reacted.
- Threads: Reply in thread opens a thread view (the root, then its
replies, older ones fetched from /relations, new ones live from the room
timeline) with a composer that sends into the thread. Thread replies
are hidden from the main timeline; the root shows "N replies". Room info
lists the room's threads (/threads).
The composer moved out of the room screen into widgets/composer.dart so
the room and thread views share it.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
