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/components/user-profile/UserRoomProfile.tsx

@@ -237,7 +237,7 @@ export function UserRoomProfile({ userId }: UserRoomProfileProps) {
       <Box direction="Column" gap="500" style={{ padding: config.space.S400 }}>
         <Box direction="Column" gap="400">
           <Box gap="400" alignItems="Center">
-            <UserHeroName displayName={displayName} userId={userId} />
+            <UserHeroName displayName={displayName} userId={userId} status={presence?.status} />
             {showEncryption && <MemberVerificationBadge userId={userId} />}
             {userId !== myUserId && (
               <Box shrink="No">