feat: add mobile shell and unified search

apps/mobile-rn/__tests__/screen-header.test.tsx

@@ -0,0 +1,48 @@
+import React from 'react'
+import { act, create, type ReactTestRenderer } from 'react-test-renderer'
+import { StyleSheet } from 'react-native'
+
+const mockGoBack = jest.fn()
+
+jest.mock('@react-navigation/native', () => ({
+  useNavigation: () => ({ goBack: mockGoBack }),
+}))
+jest.mock('react-native-safe-area-context', () => ({
+  useSafeAreaInsets: () => ({ top: 10, bottom: 0, left: 0, right: 0 }),
+}))
+jest.mock('@d3ro/i18n', () => ({
+  useI18n: () => ({ t: (key: string) => key }),
+}))
+jest.mock('../src/lib/preferences-context', () => ({
+  useMobilePreferences: () => ({
+    palette: {
+      bg: { sidebar: '#111827' },
+      text: { primary: '#ffffff', secondary: '#d1d5db', tertiary: '#9ca3af' },
+      border: { default: '#374151' },
+      accent: { light: '#60a5fa', ink: '#ffffff' },
+      tag: { green: '#34d399', red: '#f87171' },
+      status: { success: '#34d399', danger: '#f87171' },
+      overlay: { soft: 'rgba(255,255,255,0.06)' },
+    },
+  }),
+}))
+
+import { ScreenHeader } from '../src/components/ScreenHeader'
+
+describe('ScreenHeader', () => {
+  test('renders a 48dp back action for stack screens and omits it for tab roots', () => {
+    let renderer: ReactTestRenderer
+    act(() => {
+      renderer = create(<ScreenHeader title="Title" testID="header" />)
+    })
+
+    const back = renderer!.root.findByProps({ accessibilityLabel: 'common.back' })
+    expect(StyleSheet.flatten(back.props.style({ pressed: false })).width).toBe(48)
+    act(() => back.props.onPress())
+    expect(mockGoBack).toHaveBeenCalledTimes(1)
+
+    act(() => renderer!.update(<ScreenHeader title="Title" showBack={false} />))
+    expect(renderer!.root.findAllByProps({ accessibilityLabel: 'common.back' })).toHaveLength(0)
+    act(() => renderer!.unmount())
+  })
+})