Refactor to remove slices and environments, replace with instances.

app/Models/Instance.php

@@ -0,0 +1,34 @@
+<?php
+
+namespace App\Models;
+
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\BelongsTo;
+use Illuminate\Database\Eloquent\Relations\MorphMany;
+
+class Instance extends Model
+{
+    protected $guarded = [];
+
+    protected function casts(): array
+    {
+        return [
+            'config' => 'array',
+        ];
+    }
+
+    public function application(): BelongsTo
+    {
+        return $this->belongsTo(Application::class);
+    }
+
+    public function server(): BelongsTo
+    {
+        return $this->belongsTo(Server::class);
+    }
+
+    public function deployments(): MorphMany
+    {
+        return $this->morphMany(Deployment::class, 'target');
+    }
+}