feat: birthday validation integrated into profile

backend/internal/validation/custom.go

@@ -21,6 +21,7 @@ import (
 	"easywish/config"
 	"fmt"
 	"regexp"
+	"time"
 
 	"github.com/go-playground/validator/v10"
 )
@@ -55,6 +56,22 @@ func GetCustomHandlers() []CustomValidatorHandler {
         return regexp.MustCompile(`^.{1,512}$`).MatchString(username)
 		}},
 
+		{
+			FieldName: "birthday_unix_milli",
+			Function: func(fl validator.FieldLevel) bool {
+			
+			timestamp := fl.Field().Int()
+			date := time.UnixMilli(timestamp)
+			currentDate := time.Now()
+
+			age := currentDate.Year() - date.Year()
+			if currentDate.YearDay() < date.YearDay() {
+				age--
+			}
+
+			return age >= 0 && age <= 122
+		}},
+
 		{
 			FieldName: "color_hex",
 			Function: func(fl validator.FieldLevel) bool {