feat: custom status message — display + editor with emoji picker

- MembersDrawer: show presence.status as small muted text below
  username in every member row (live via useUserPresence)
- UserHero/UserHeroName: accept optional status prop; render below
  the @username handle in user profile popouts
- UserRoomProfile: pass presence?.status down to UserHeroName
- Profile settings: new ProfileStatus tile below Display Name
  * Input with inline emoji picker (lazy-loaded EmojiBoard)
  * Cursor-aware emoji insertion (preserves caret position)
  * Save via mx.setPresence({ status_msg }) / Clear button
  * Pre-fills from current presence; syncs on remote update

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/app/features/room/MembersDrawer.tsx

@@ -167,10 +167,15 @@ function MemberItem({
         </>
       }
     >
-      <Box grow="Yes">
+      <Box grow="Yes" direction="Column">
         <Text size="T400" truncate>
           {name}
         </Text>
+        {presence?.status && (
+          <Text size="T200" truncate style={{ opacity: 0.65 }}>
+            {presence.status}
+          </Text>
+        )}
       </Box>
     </MenuItem>
   );