refactor: organize service dto contracts

internal/server/handler/email.go

@@ -2,6 +2,7 @@ package handler
 
 import (
 	"kra/internal/service"
+	"kra/internal/service/dto"
 
 	"github.com/gin-gonic/gin"
 )
@@ -19,7 +20,7 @@ func (h *Email) Test(c *gin.Context) {
 }
 
 func (h *Email) Send(c *gin.Context) {
-	var req service.SendEmailRequest
+	var req dto.SendEmailRequest
 	if err := c.ShouldBindJSON(&req); err != nil {
 		Fail(c, err.Error())
 		return