feat: Expo mobile scaffold — Phase 2 complete (118-file structure)

Expo SDK 51 TypeScript scaffold with all architecture files.
Verified: tsc 0 errors, jest passes.

mobile/jest.setup.ts

@@ -0,0 +1,11 @@
+jest.mock('@react-native-async-storage/async-storage', () =>
+  require('@react-native-async-storage/async-storage/jest/async-storage-mock')
+);
+
+jest.mock('react-native-wifi-reborn', () => ({
+  loadWifiList: jest.fn(async () => []),
+}));
+
+jest.mock('react-native-reanimated', () =>
+  require('react-native-reanimated/mock')
+);