feat: add seeder

database/seeders/SlotSeeder.php

@@ -0,0 +1,17 @@
+<?php
+
+namespace Database\Seeders;
+
+use App\Models\Slot;
+use Illuminate\Database\Seeder;
+
+class SlotSeeder extends Seeder
+{
+    public function run(): void
+    {
+        Slot::query()->upsert([
+            ['id' => 1, 'capacity' => 10, 'remaining' => 10],
+            ['id' => 2, 'capacity' => 5, 'remaining' => 5],
+        ], ['id'], ['capacity', 'remaining']);
+    }
+}