fix(desktop): mask composer rounded corners (#2165)

desktop/src/features/channels/ui/ChannelPane.tsx

@@ -734,7 +734,7 @@ export const ChannelPane = React.memo(function ChannelPane({
               data-testid="channel-composer-overlay"
               ref={composerWrapperRef}
             >
-              <div className="pointer-events-auto">
+              <div className="composer-overlay-corner-masks pointer-events-auto">
                 {timeoutState.active ? (
                   <ComposerTimeoutBanner
                     expiresAtMs={timeoutState.expiresAtMs}

desktop/src/features/messages/ui/MessageThreadPanel.tsx

@@ -816,7 +816,7 @@ export function MessageThreadPanel({
       >
         <div
           className={cn(
-            "pointer-events-auto",
+            "composer-overlay-corner-masks pointer-events-auto",
             hasConstrainedColumn && THREAD_PANEL_COLUMN_CLASS,
           )}
           style={