✨ 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).

tests/Feature/Mcp/CityMcpToolTest.php

@@ -0,0 +1,73 @@
+<?php
+
+use App\Mcp\Servers\EinundzwanzigServer;
+use App\Mcp\Tools\City\CreateCityTool;
+use App\Mcp\Tools\City\ListMyCitiesTool;
+use App\Mcp\Tools\City\ShowMyCityTool;
+use App\Mcp\Tools\City\UpdateCityTool;
+use App\Models\City;
+use App\Models\Country;
+use App\Models\User;
+
+it('lets an authenticated user create a city and stamps created_by', function () {
+    $user = User::factory()->create();
+    $country = Country::factory()->create();
+
+    $response = EinundzwanzigServer::actingAs($user)->tool(CreateCityTool::class, [
+        'name' => 'Ansbach',
+        'country_id' => $country->id,
+        'longitude' => 10.5806,
+        'latitude' => 49.3034,
+    ]);
+
+    $response->assertOk()->assertSee('Ansbach');
+
+    $this->assertDatabaseHas('cities', [
+        'name' => 'Ansbach',
+        'created_by' => $user->id,
+    ]);
+});
+
+it('fails validation for missing fields', function () {
+    EinundzwanzigServer::actingAs(User::factory()->create())
+        ->tool(CreateCityTool::class, [])
+        ->assertHasErrors();
+});
+
+it('lets the owner update a city', function () {
+    $user = User::factory()->create();
+    $city = City::factory()->create(['created_by' => $user->id]);
+
+    EinundzwanzigServer::actingAs($user)
+        ->tool(UpdateCityTool::class, ['id' => $city->id, 'name' => 'Nürnberg'])
+        ->assertOk()
+        ->assertSee('Nürnberg');
+});
+
+it('forbids updating someone elses city', function () {
+    $owner = User::factory()->create();
+    $city = City::factory()->create(['created_by' => $owner->id]);
+
+    EinundzwanzigServer::actingAs(User::factory()->create())
+        ->tool(UpdateCityTool::class, ['id' => $city->id, 'name' => 'Hijack'])
+        ->assertHasErrors();
+});
+
+it('returns only own cities in the mine list', function () {
+    $user = User::factory()->create();
+    City::factory()->count(2)->create(['created_by' => $user->id]);
+    City::factory()->create(['created_by' => User::factory()->create()->id]);
+
+    EinundzwanzigServer::actingAs($user)
+        ->tool(ListMyCitiesTool::class)
+        ->assertOk();
+});
+
+it('forbids viewing someone elses city in mine show', function () {
+    $owner = User::factory()->create();
+    $city = City::factory()->create(['created_by' => $owner->id]);
+
+    EinundzwanzigServer::actingAs(User::factory()->create())
+        ->tool(ShowMyCityTool::class, ['id' => $city->id])
+        ->assertHasErrors();
+});