Add formula-based product pricing (P/W/MG) for Parsian-style unit prices.

Port FormulaPriceService from colleague app so admins can compute a single unit price from reference mid, weight, and wage instead of offset coefficients.

Co-authored-by: Cursor <cursoragent@cursor.com>

app/Models/Product.php

@@ -28,6 +28,7 @@ class Product extends Model
     private static ?bool $cashFeePercentModeColumnsExist = null;
     private static ?bool $physicalDeliveryColumnsExist = null;
     private static ?bool $descriptionColumnExists = null;
+    private static ?bool $priceFormulaColumnsExist = null;
 
     protected static function booted(): void
     {
@@ -78,9 +79,32 @@ class Product extends Model
                     $product->attributes['min_physical_delivery_quantity']
                 );
             }
+            if (!static::hasPriceFormulaColumns()) {
+                unset(
+                    $product->attributes['price_formula_enabled'],
+                    $product->attributes['price_formula']
+                );
+            }
         });
     }
 
+    public static function hasPriceFormulaColumns(): bool
+    {
+        if (static::$priceFormulaColumnsExist !== null) {
+            return static::$priceFormulaColumnsExist;
+        }
+
+        try {
+            $table = (new static)->getTable();
+            static::$priceFormulaColumnsExist = Schema::hasColumn($table, 'price_formula_enabled')
+                && Schema::hasColumn($table, 'price_formula');
+        } catch (\Throwable) {
+            static::$priceFormulaColumnsExist = false;
+        }
+
+        return static::$priceFormulaColumnsExist;
+    }
+
     public static function hasPhysicalDeliveryColumns(): bool
     {
         if (static::$physicalDeliveryColumnsExist !== null) {
@@ -418,6 +442,8 @@ class Product extends Model
         'description',
         'direct_price',
         'app_price',            // روشن: قیمت واحد از قیمت زندهٔ اپ هر گرم × وزن محاسبه می‌شود
+        'price_formula_enabled',
+        'price_formula',
     ];
 
     protected $attributes = [
@@ -427,6 +453,7 @@ class Product extends Model
         'cash_fee_buy_is_percent' => false,
         'cash_fee_sell_is_percent' => false,
         'app_price' => false,
+        'price_formula_enabled' => false,
     ];
 
     protected $casts = [
@@ -457,6 +484,7 @@ class Product extends Model
         'price_offset_percent' => 'float',
         'price_profit' => 'int',
         'app_price' => 'boolean',
+        'price_formula_enabled' => 'boolean',
     ];
 
     static $METAL_ID = [