feat(smart-app): implement complete mobile app MVP

- App.tsx: full navigation (Auth stack + Main tabs with 5 screens)
- Auth: LoginScreen, RegisterScreen, ForgotPasswordScreen
- HomeScreen: dashboard with IoT metrics, weather widget, alerts, quick actions, sensors
- MapScreen: interactive map with layer toggles (6 layers)
- MarketplaceScreen: categories (6), products (5), search
- ChatScreen: AI chat with quick prompts (4), bot responses
- ProfileScreen: user info, stats, menu (9 items), logout
- AlertsScreen: alert list with severity, acknowledge
- SensorsScreen: sensor list with type filters (6 types), search
- ZonesScreen: zone cards with stats
- SettingsScreen: language picker (FR/EN/ES/DE), privacy, about
- Stores: iotStore (sensors, zones, alerts), notificationStore, uiStore + i18n
- Hooks: useSensors, useAlerts, useNotifications, useLocation
- Components: Card, Button, LoadingSpinner, ErrorBoundary, Header
- Services: iotService, notificationService (with axios API client)
- Utils: formatters (temp, AQI, noise, dates), validators (email, password, IBAN)
- Theme: colors.ts with full design system (Blue Ocean palette)
- Ditto: fixed MongoDB connection, new JWT secrets, official gateway image

smart-app-city/frontend/node_modules/react-native/android/README.md

@@ -0,0 +1,21 @@
+# The `/android` folder inside `react-native`
+
+Starting from React Native 0.71, we're not shipping the `/android` folder inside the React Native NPM package
+anymore due to sizing constraints on NPM. The Android artifacts are distributed via Maven Central.
+You can read more about it in this RFC:
+https://github.com/react-native-community/discussions-and-proposals/pull/508
+
+If you're a library author and you're manipulating the React Native .aar files, to extract headers,
+extract `.so` files or do anything with it, you're probably doing something wrong. React Native
+0.71 ships with all the necessary logic to let you consume it transparently by just using:
+
+```
+implementation("com.facebook.react:react-android")
+// or to keep backward compatibility with older versions of React Native:
+implementation("com.facebook.react:react-native:+")
+```
+
+You should consider refactoring your library code not to unzip/manipulate the React Native .aar files.
+
+This README.md file is kept in this folder as some libraries are checking the existence of the `/android` folder
+and failing user builds if the folder is missing.