fix: clean up VSCode settings duplication and hide irrelevant sections

Remove mermaidRendering, userMessageRendering, stickyUserHeader from Appearance in VSCode (already in Chat)
Hide Navigation settings (navRail, terminalQuickKeys) in VSCode Appearance
Hide Shortcuts section entirely in VSCode

packages/ui/src/components/sections/openchamber/OpenChamberPage.tsx

@@ -103,7 +103,7 @@ const ShortcutsSectionContent: React.FC = () => {
 // Visual section: Theme Mode, Font Size, Spacing, Corner Radius, Input Bar Offset (mobile), Nav Rail
 const VisualSectionContent: React.FC = () => {
     const isVSCode = isVSCodeRuntime();
-    const visibleSettings: Array<'theme' | 'pwaInstallName' | 'fontSize' | 'terminalFontSize' | 'spacing' | 'cornerRadius' | 'inputBarOffset' | 'terminalQuickKeys' | 'navRail' | 'mermaidRendering' | 'userMessageRendering' | 'stickyUserHeader'> = [
+    return <OpenChamberVisualSettings visibleSettings={[
         'theme',
         'pwaInstallName',
         'fontSize',
@@ -111,15 +111,8 @@ const VisualSectionContent: React.FC = () => {
         'spacing',
         'cornerRadius',
         'inputBarOffset',
-        'terminalQuickKeys',
-        'navRail',
-    ];
-
-    if (isVSCode) {
-        visibleSettings.push('mermaidRendering', 'userMessageRendering', 'stickyUserHeader');
-    }
-
-    return <OpenChamberVisualSettings visibleSettings={visibleSettings} />;
+        ...(!isVSCode ? ['terminalQuickKeys' as const, 'navRail' as const] : []),
+    ]} />;
 };
 
 // Chat section: Default Tool Output, User message rendering, Diff layout, Mobile status bar, Show reasoning traces, Queue mode, Persist draft

packages/ui/src/components/sections/openchamber/OpenChamberVisualSettings.tsx

@@ -418,7 +418,7 @@ export const OpenChamberVisualSettings: React.FC<OpenChamberVisualSettingsProps>
                                 <div className={cn('py-1.5', isMobile ? 'space-y-2' : 'flex items-center gap-8')}>
                                     <div className={cn('flex min-w-0 flex-col', isMobile ? 'w-full' : 'w-56 shrink-0')}>
                                         <span className="typography-ui-label text-foreground">Install App Name</span>
-                                        <span className="typography-meta text-muted-foreground">Used by Chrome install prompt before install.</span>
+                                        <span className="typography-meta text-muted-foreground">Used by PWA installation process.</span>
                                     </div>
                                     <div className={cn('flex items-center gap-2', isMobile ? 'w-full' : 'w-fit min-w-[22rem]')}>
                                         <Input

packages/ui/src/lib/settings/metadata.ts

@@ -158,6 +158,7 @@ export const SETTINGS_PAGE_METADATA: readonly SettingsPageMeta[] = [
     group: 'general',
     kind: 'single',
     keywords: ['keyboard', 'hotkeys', 'shortcuts', 'bindings'],
+    isAvailable: (ctx) => !ctx.isVSCode,
   },
   {
     slug: 'sessions',