feat: add stock movement on backend

backend/models/stock.go

@@ -0,0 +1,17 @@
+package models
+
+import (
+	"time"
+)
+
+type StockMovement struct {
+	ID        uint    `json:"id" gorm:"primaryKey"`
+	ItemID    uint    `json:"item_id"`
+	Item      Item    `json:"item" gorm:"foreignKey:ItemID"`
+	Type      string  `json:"type"`
+	Quantity  float64 `json:"quantity"`
+	Reason    string  `json:"reason" gorm:"not null"`
+	OrderID   *uint   `json:"order_id"`
+	Comment   string  `json:"comment"`
+	CreatedAt time.Time
+}