Update guest v2 branding and theming

resources/js/admin/mobile/__tests__/BrandingPage.test.tsx

@@ -99,6 +99,10 @@ vi.mock('@tamagui/text', () => ({
   SizableText: ({ children }: { children: React.ReactNode }) => <span>{children}</span>,
 }));
 
+vi.mock('@tamagui/core', () => ({
+  Theme: ({ children }: { children: React.ReactNode }) => <div>{children}</div>,
+}));
+
 vi.mock('@tamagui/react-native-web-lite', () => ({
   Pressable: ({ children, onPress }: { children: React.ReactNode; onPress?: () => void }) => (
     <button type="button" onClick={onPress}>