refactor(catalog): Complete catalog refactor to simplify its data model and its querying.

source commits: refactor/catalog

app/Domains/Catalog/Models/VariantDefinition.php

@@ -0,0 +1,32 @@
+<?php
+
+namespace App\Domains\Catalog\Models;
+
+use Illuminate\Database\Eloquent\Attributes\Fillable;
+use Illuminate\Database\Eloquent\Factories\HasFactory;
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\BelongsTo;
+
+#[Fillable([
+    'variant_id',
+    'item_attribute_id',
+    'value',
+])]
+class VariantDefinition extends Model
+{
+    use HasFactory;
+
+    protected $table = 'variant_values';
+
+    /** @return BelongsTo<Variant, $this> */
+    public function variant(): BelongsTo
+    {
+        return $this->belongsTo(Variant::class);
+    }
+
+    /** @return BelongsTo<ItemAttribute, $this> */
+    public function itemAttribute(): BelongsTo
+    {
+        return $this->belongsTo(ItemAttribute::class);
+    }
+}