feat: add City10 platform with Laravel 13, AI agents, 3D viewer, and LGPD compliance

Initial commit of the complete City10 virtual city simulation platform.

Backend (Laravel 13):
- REST API with Sanctum tokens and session-based web authentication
- Role-based access control (admin/user) with middleware protection
- AI agent CRUD with OpenRouter.ai integration restricted to free models
- Store management with 3D coordinates and AI shopkeeper assignment
- Versioned legal documents (Terms, Privacy, Cookies) with LGPD audit trail
- Math CAPTCHA on public forms and multi-language support (pt_BR, en, es)

Frontend:
- Responsive Blade templates with Tailwind CSS v4
- Three.js 3D city viewer with SSE chat streaming to AI agents
- Admin panel for store and user administration

Infrastructure:
- MariaDB/MySQL database with comprehensive migrations
- Database seeders for demo content and test accounts
- PHPUnit test suite and Laravel Pint code styling
- Vite build configuration with hot reload

app/Http/Controllers/Web/LanguageController.php

@@ -0,0 +1,43 @@
+<?php
+
+namespace App\Http\Controllers\Web;
+
+use App\Http\Controllers\Controller;
+use Illuminate\Http\RedirectResponse;
+use Illuminate\Http\Request;
+use Illuminate\Support\Facades\App;
+
+/**
+ * Language switcher controller.
+ *
+ * Persists the selected locale (pt_BR, en, es) in the session and in the
+ * user's profile when authenticated, so the whole UI is rendered in the
+ * language chosen from the dashboard or the public pages.
+ */
+class LanguageController extends Controller
+{
+    /**
+     * Switch the application locale for the current visitor.
+     */
+    public function switch(Request $request): RedirectResponse
+    {
+        $locale = $request->input('locale');
+
+        if (! in_array($locale, ['pt_BR', 'en', 'es'], true)) {
+            return back();
+        }
+
+        App::setLocale($locale);
+        $request->session()->put('locale', $locale);
+
+        if ($user = $request->user()) {
+            $user->update(['locale' => $locale]);
+        }
+
+        // Persist the cookie preference (1 year) used on subsequent visits.
+        $response = back();
+        $response->withCookie(cookie('city10-locale', $locale, 60 * 24 * 365, '/', null, false, true));
+
+        return $response;
+    }
+}