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/app.config.ts

@@ -0,0 +1,12 @@
+export default {
+  name: 'WiFi-DensePose',
+  slug: 'wifi-densepose',
+  version: '1.0.0',
+  ios: {
+    bundleIdentifier: 'com.ruvnet.wifidensepose',
+  },
+  android: {
+    package: 'com.ruvnet.wifidensepose',
+  },
+  // Use expo-env and app-level defaults from the project configuration when available.
+};