fix: hide "Back to Mail" in settings when Pro mode is on

app/(main)/[locale]/settings/page.tsx

@@ -363,6 +363,7 @@ export default function SettingsPage() {
   const installedPlugins = usePluginStore((s) => s.plugins);
   const installedThemes = useThemeStore((s) => s.installedThemes);
   const sidebarAppsList = useSettingsStore((s) => s.sidebarApps);
+  const proInterface = useSettingsStore((s) => s.proInterface);
 
   // Build a per-tab haystack for fulltext search and a list of sub-results
   // (individual settings) per tab. Sub-results come from translation entries
@@ -866,6 +867,7 @@ export default function SettingsPage() {
         )}
         style={{ width: `${settingsSidebarWidth}px` }}
       >
+        {!proInterface && (
           <div className="p-4 border-b border-border">
             <Button
               variant="ghost"
@@ -877,6 +879,7 @@ export default function SettingsPage() {
               {t('back_to_mail')}
             </Button>
           </div>
+        )}
 
         <div className="flex-1 overflow-y-auto py-2" data-tour="settings-tabs">
           <div className="px-3 pt-1 pb-1">