feat: add slug field to events and implement tests for slug uniqueness per tenant

tests/Feature/Migrations/AddSlugsToEventsTest.php

@@ -0,0 +1,37 @@
+<?php
+
+namespace Tests\Feature\Migrations;
+
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\DB;
+use Illuminate\Support\Facades\Schema;
+use Tests\TestCase;
+
+class AddSlugsToEventsTest extends TestCase
+{
+    public function test_it_backfills_unique_slugs_per_tenant(): void
+    {
+        Schema::create('events', function (Blueprint $table): void {
+            $table->id();
+            $table->string('tenant_code');
+            $table->string('title');
+        });
+
+        DB::table('events')->insert([
+            ['id' => 1, 'tenant_code' => 'acme', 'title' => 'Gran Fiesta'],
+            ['id' => 2, 'tenant_code' => 'acme', 'title' => 'Gran Fiesta'],
+            ['id' => 3, 'tenant_code' => 'other', 'title' => 'Gran Fiesta'],
+            ['id' => 4, 'tenant_code' => 'acme', 'title' => '---'],
+        ]);
+
+        $migration = require database_path('migrations/2026_09_22_010000_add_slugs_to_events.php');
+        $migration->up();
+
+        $this->assertSame([
+            1 => 'gran-fiesta',
+            2 => 'gran-fiesta-2',
+            3 => 'gran-fiesta',
+            4 => 'evento-4',
+        ], DB::table('events')->orderBy('id')->pluck('slug', 'id')->all());
+    }
+}