feat(catalog): track variant replacements

app/Domains/Catalog/Models/Inventory.php

@@ -42,10 +42,10 @@ class Inventory extends Model
         return $this->hasOne(CatalogItem::class);
     }
 
-    /** @return HasOne<Variant, $this> */
-    public function variant(): HasOne
+    /** @return HasMany<Variant, $this> */
+    public function variants(): HasMany
     {
-        return $this->hasOne(Variant::class);
+        return $this->hasMany(Variant::class);
     }
 
     /** @return HasMany<StockReservationLine, $this> */

app/Domains/Catalog/Models/Variant.php

@@ -20,6 +20,8 @@ use Illuminate\Support\Str;
     'catalog_item_id',
     'event_date_id',
     'inventory_id',
+    'replaced_by_variant_id',
+    'sales_disabled_at',
     'descripcion',
     'precio',
 ])]
@@ -37,6 +39,8 @@ class Variant extends Model
             'catalog_item_id' => 'integer',
             'event_date_id' => 'integer',
             'inventory_id' => 'integer',
+            'replaced_by_variant_id' => 'integer',
+            'sales_disabled_at' => 'datetime',
             'precio' => 'decimal:2',
         ];
     }
@@ -76,6 +80,24 @@ class Variant extends Model
         return $this->belongsTo(Inventory::class);
     }
 
+    /** @return BelongsTo<Variant, $this> */
+    public function replacement(): BelongsTo
+    {
+        return $this->belongsTo(self::class, 'replaced_by_variant_id');
+    }
+
+    /** @return HasMany<Variant, $this> */
+    public function replacedVariants(): HasMany
+    {
+        return $this->hasMany(self::class, 'replaced_by_variant_id');
+    }
+
+    public function isSellable(): bool
+    {
+        return $this->sales_disabled_at === null
+            && $this->replaced_by_variant_id === null;
+    }
+
     /** @return HasMany<VariantDefinition, $this> */
     public function definitions(): HasMany
     {