✨ Add OAuth functionality, MCP tools, and feature tests

- 🔒 Added migrations for `oauth_access_tokens`, `oauth_refresh_tokens`, `oauth_auth_codes`, `oauth_clients`, and `oauth_device_codes`.
- 🤖 Created MCP tools (Meetups, Cities, Venues, Courses, Lecturers) for managing entities with authentication and validation.
- 🛠️ Implemented Passport-backed OAuth API guard configuration and validation endpoints.
- ✅ Added comprehensive feature tests for MCP tools and OAuth functionality (access control, validation, and token-based authentication).

app/Mcp/Tools/City/CreateCityTool.php

@@ -0,0 +1,52 @@
+<?php
+
+namespace App\Mcp\Tools\City;
+
+use App\Http\Requests\Api\StoreCityRequest;
+use App\Http\Resources\CityResource;
+use App\Models\City;
+use Illuminate\Contracts\JsonSchema\JsonSchema;
+use Illuminate\JsonSchema\Types\Type;
+use Illuminate\Support\Facades\Gate;
+use Laravel\Mcp\Request;
+use Laravel\Mcp\Response;
+use Laravel\Mcp\Server\Attributes\Description;
+use Laravel\Mcp\Server\Tool;
+
+#[Description('Legt eine neue Stadt für den authentifizierten Nutzer an. Der Ersteller (created_by) wird automatisch gesetzt.')]
+class CreateCityTool extends Tool
+{
+    public function handle(Request $request): Response
+    {
+        $user = $request->user();
+
+        if ($user === null || Gate::forUser($user)->denies('create', City::class)) {
+            return Response::error('Nicht berechtigt, eine Stadt anzulegen.');
+        }
+
+        $storeRequest = new StoreCityRequest;
+
+        $validated = $request->validate(
+            $storeRequest->rules(),
+            $storeRequest->messages(),
+        );
+
+        $city = City::create($validated);
+
+        return Response::json(CityResource::make($city->fresh())->resolve());
+    }
+
+    /**
+     * @return array<string, Type>
+     */
+    public function schema(JsonSchema $schema): array
+    {
+        return [
+            'country_id' => $schema->integer()->description('ID des zugehörigen Landes.')->required(),
+            'name' => $schema->string()->description('Name der Stadt.')->required(),
+            'longitude' => $schema->number()->description('Längengrad der Stadt.')->required(),
+            'latitude' => $schema->number()->description('Breitengrad der Stadt.')->required(),
+            'population' => $schema->integer()->description('Einwohnerzahl der Stadt.'),
+        ];
+    }
+}