fix(ui): receipt pill, insights counts, settings dividers, decoration preview (#269-#273)

#269 read-receipt pill sits at the message row's right edge, not where
     the text ends (outside the shrink-to-fit content column; grows in
     Compact). Bubble layout unchanged.
#270 Most Active Members: the bar's % is of its own track, so every row
     shows its count.
#271 Noise Suppression description at T200 like the rest.
#272 decoration preview shows your own avatar under the decoration; the
     empty state is a visible dashed circle.
#273 grouped settings get a divider between tiles (SettingTileGroup, via
     globalStyle; SettingTile roots carry data-setting-tile), and on phones
     the Sync tile's buttons sit under its description.

Fixes #269
Fixes #270
Fixes #271
Fixes #272
Fixes #273

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017PCb59uY3UKqDqt7B6hzd5

src/app/components/setting-tile/SettingTile.tsx

@@ -34,7 +34,8 @@ export function SettingTile({ title, description, before, after, children }: Set
   });
 
   return (
-    <Box alignItems="Center" gap="300">
+    // data-setting-tile: lets a group card draw dividers between tiles only (#273).
+    <Box alignItems="Center" gap="300" data-setting-tile="">
       {before && <Box shrink="No">{before}</Box>}
       <Box grow="Yes" direction="Column" gap="100">
         {title && (