feat(yggdrasil): implement standard error responses and UUID format improvements

- Add YggdrasilErrorResponse struct and standard error codes for protocol compliance
- Change UUID storage from varchar(36) to varchar(32) for unsigned format
- Add utility functions: GenerateUUID, FormatUUIDToNoDash, RandomHex
- Support unsigned query parameter in GetProfileByUUID endpoint
- Improve refresh token response with available profiles list
- Fix key pair retrieval to use correct database column (rsa_private_key)
- Update UUID validator to accept both 32-char and 36-char formats
- Add SignStringWithProfileRSA method for profile-specific signing
- Fix profile assignment validation in refresh token flow

internal/service/captcha_service.go

@@ -3,13 +3,13 @@ package service
 import (
 	"carrotskin/pkg/config"
 	"carrotskin/pkg/redis"
+	"carrotskin/pkg/utils"
 	"context"
 	"errors"
 	"fmt"
 	"log"
 	"time"
 
-	"github.com/google/uuid"
 	"github.com/wenlng/go-captcha-assets/resources/imagesv2"
 	"github.com/wenlng/go-captcha-assets/resources/tiles"
 	"github.com/wenlng/go-captcha/v2/slide"
@@ -87,7 +87,7 @@ func NewCaptchaService(redisClient *redis.Client, logger *zap.Logger) CaptchaSer
 // Generate 生成验证码
 func (s *captchaService) Generate(ctx context.Context) (masterImg, tileImg, captchaID string, y int, err error) {
 	// 生成uuid作为验证码进程唯一标识
-	captchaID = uuid.NewString()
+	captchaID = utils.GenerateUUID()
 	if captchaID == "" {
 		err = errors.New("生成验证码唯一标识失败")
 		return