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/expo-location/src/GeolocationPolyfill.ts

@@ -0,0 +1,92 @@
+import { Platform } from 'expo-modules-core';
+
+import ExpoLocation from './ExpoLocation';
+import { LocationObject, LocationAccuracy, LocationOptions } from './Location.types';
+import { LocationSubscriber } from './LocationSubscribers';
+
+type GeolocationSuccessCallback = (data: LocationObject) => void;
+type GeolocationErrorCallback = (error: any) => void;
+
+type GeolocationOptions = {
+  enableHighAccuracy?: boolean;
+};
+
+declare const global: any;
+
+// @needsAudit
+/**
+ * Polyfills `navigator.geolocation` for interop with the core React Native and Web API approach to geolocation.
+ */
+export function installWebGeolocationPolyfill(): void {
+  if (Platform.OS !== 'web') {
+    // Make sure `window.navigator` is defined in the global scope.
+    if (!('window' in global)) {
+      global.window = global;
+    }
+    if (!('navigator' in global.window)) {
+      global.window.navigator = {};
+    }
+
+    // @ts-ignore
+    window.navigator.geolocation = {
+      getCurrentPosition,
+      watchPosition,
+      clearWatch,
+
+      // We don't polyfill stopObserving, this is an internal method that probably should not even exist
+      // in react-native docs
+      stopObserving: () => {},
+    };
+  }
+}
+
+function convertGeolocationOptions(options: GeolocationOptions): LocationOptions {
+  return {
+    accuracy: options.enableHighAccuracy ? LocationAccuracy.High : LocationAccuracy.Balanced,
+  };
+}
+
+function getCurrentPosition(
+  success: GeolocationSuccessCallback,
+  error: GeolocationErrorCallback = () => {},
+  options: GeolocationOptions = {}
+): void {
+  _getCurrentPositionAsyncWrapper(success, error, options);
+}
+
+// This function exists to let us continue to return undefined from getCurrentPosition, while still
+// using async/await for the internal implementation of it
+async function _getCurrentPositionAsyncWrapper(
+  success: GeolocationSuccessCallback,
+  error: GeolocationErrorCallback,
+  options: GeolocationOptions
+): Promise<any> {
+  try {
+    await ExpoLocation.requestPermissionsAsync();
+    const result = await ExpoLocation.getCurrentPositionAsync(convertGeolocationOptions(options));
+    success(result);
+  } catch (e) {
+    error(e);
+  }
+}
+
+// Polyfill: navigator.geolocation.watchPosition
+function watchPosition(
+  success: GeolocationSuccessCallback,
+  error: GeolocationErrorCallback,
+  options: GeolocationOptions
+) {
+  const watchId = LocationSubscriber.registerCallback(success);
+
+  ExpoLocation.watchPositionImplAsync(watchId, options).catch((err) => {
+    LocationSubscriber.unregisterCallback(watchId);
+    error({ watchId, message: err.message, code: err.code });
+  });
+
+  return watchId;
+}
+
+// Polyfill: navigator.geolocation.clearWatch
+function clearWatch(watchId: number) {
+  LocationSubscriber.unregisterCallback(watchId);
+}