chore: global mode doesn't show proxy groups, use placeholder images instead

src/components/proxy/proxy-groups.tsx

@@ -121,6 +121,10 @@ export const ProxyGroups = (props: Props) => {
     return <BaseEmpty text={t("clash_mode_direct")} />;
   }
 
+  if (mode === "global") {
+    return <BaseEmpty text={t("clash_mode_global")} />;
+  }
+
   return (
     <Virtuoso
       ref={virtuosoRef}