Add swipe-to-open sidebar on first tab

When swiping right on the first tab, opens the mobile sidebar menu.
Added onSwipePastStart prop to SwipeTabs component.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/src/pages/admin/ThemeSettings.tsx

@@ -45,7 +45,7 @@ export default function ThemeSettings() {
     } = useTheme();
     const { t } = useTranslation();
     const { user } = useAuth();
-    const { toggleMobileMenu, sidebarMode, setSidebarMode } = useSidebar();
+    const { toggleMobileMenu, openMobileMenu, sidebarMode, setSidebarMode } = useSidebar();
     const isAdmin = user?.is_superuser || false;
     const tabs: ThemeTab[] = isAdmin ? ['colors', 'appearance', 'preview', 'advanced'] : ['colors', 'appearance', 'preview'];
     const [tooltip, setTooltip] = useState<{ text: string; left: number; visible: boolean }>({
@@ -764,6 +764,7 @@ export default function ThemeSettings() {
                 onTabChange={setActiveTab}
                 renderPanel={renderPanel}
                 panelClassName="admin-tab-content swipe-panel-content"
+                onSwipePastStart={openMobileMenu}
             />
 
             {/* Color Picker Popup */}