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/traverse/test/stringify.js

@@ -0,0 +1,35 @@
+'use strict';
+
+var test = require('tape');
+var traverse = require('../');
+
+test('stringify', function (t) {
+	var obj = [5, 6, -3, [7, 8, -2, 1], { f: 10, g: -13 }];
+
+	var s = '';
+	traverse(obj).forEach(function (node) {
+		if (Array.isArray(node)) {
+			this.before(function () { s += '['; });
+			this.post(function (child) {
+				if (!child.isLast) { s += ','; }
+			});
+			this.after(function () { s += ']'; });
+		} else if (typeof node === 'object') {
+			this.before(function () { s += '{'; });
+			this.pre(function (x, key) {
+				s += '"' + key + '":';
+			});
+			this.post(function (child) {
+				if (!child.isLast) { s += ','; }
+			});
+			this.after(function () { s += '}'; });
+		} else if (typeof node === 'function') {
+			s += 'null';
+		} else {
+			s += node.toString();
+		}
+	});
+
+	t.equal(s, JSON.stringify(obj));
+	t.end();
+});