fix(order): improve code quality and fix critical bugs in order processing logic

- Fix inconsistent logging calls across all order logic files
- Fix critical gift amount deduction logic bug in renewal process
- Fix variable shadowing errors in database transactions
- Add comprehensive Go-standard documentation comments
- Improve log prefix consistency for better debugging
- Remove redundant discount validation code

internal/logic/public/order/getDiscount.go

@@ -10,5 +10,6 @@ func getDiscount(discounts []types.SubscribeDiscount, inputMonths int64) float64
 			finalDiscount = discount.Discount
 		}
 	}
+
 	return float64(finalDiscount) / float64(100)
 }