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/postcss/README.md

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+# PostCSS
+
+<img align="right" width="95" height="95"
+     alt="Philosopher’s stone, logo of PostCSS"
+     src="https://postcss.org/logo.svg">
+
+PostCSS is a tool for transforming styles with JS plugins.
+These plugins can lint your CSS, support variables and mixins,
+transpile future CSS syntax, inline images, and more.
+
+PostCSS is used by industry leaders including Wikipedia, Twitter, Alibaba,
+and JetBrains. The [Autoprefixer] and [Stylelint] PostCSS plugins is one of the most popular CSS tools.
+
+---
+
+<img src="https://cdn.evilmartians.com/badges/logo-no-label.svg" alt="" width="22" height="16" />  Made at <b><a href="https://evilmartians.com/devtools?utm_source=postcss&utm_campaign=devtools-button&utm_medium=github">Evil Martians</a></b>, product consulting for <b>developer tools</b>.
+
+---
+
+[Abstract Syntax Tree]: https://en.wikipedia.org/wiki/Abstract_syntax_tree
+[Evil Martians]:        https://evilmartians.com/?utm_source=postcss
+[Autoprefixer]:         https://github.com/postcss/autoprefixer
+[Stylelint]:            https://stylelint.io/
+[plugins]:              https://github.com/postcss/postcss#plugins
+
+
+## Docs
+Read full docs **[here](https://postcss.org/)**.