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/braces/lib/stringify.js

@@ -0,0 +1,32 @@
+'use strict';
+
+const utils = require('./utils');
+
+module.exports = (ast, options = {}) => {
+  const stringify = (node, parent = {}) => {
+    const invalidBlock = options.escapeInvalid && utils.isInvalidBrace(parent);
+    const invalidNode = node.invalid === true && options.escapeInvalid === true;
+    let output = '';
+
+    if (node.value) {
+      if ((invalidBlock || invalidNode) && utils.isOpenOrClose(node)) {
+        return '\\' + node.value;
+      }
+      return node.value;
+    }
+
+    if (node.value) {
+      return node.value;
+    }
+
+    if (node.nodes) {
+      for (const child of node.nodes) {
+        output += stringify(child);
+      }
+    }
+    return output;
+  };
+
+  return stringify(ast);
+};
+