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/yggdrasil_validator.go

@@ -57,16 +57,38 @@ func (v *Validator) ValidateEmail(email string) error {
 	return nil
 }
 
-// ValidateUUID 验证UUID格式（简单验证）
+// ValidateUUID 验证UUID格式（支持32位无符号和36位带连字符格式）
 func (v *Validator) ValidateUUID(uuid string) error {
 	if uuid == "" {
 		return errors.New("UUID不能为空")
 	}
-	// UUID格式：xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx (32个十六进制字符 + 4个连字符)
-	if len(uuid) < 32 || len(uuid) > 36 {
-		return errors.New("UUID格式无效")
+
+	// 验证32位无符号UUID格式（纯十六进制字符串）
+	if len(uuid) == 32 {
+		// 检查是否为有效的十六进制字符串
+		for _, c := range uuid {
+			if !((c >= '0' && c <= '9') || (c >= 'a' && c <= 'f') || (c >= 'A' && c <= 'F')) {
+				return errors.New("UUID格式无效：包含非十六进制字符")
+			}
+		}
+		return nil
 	}
-	return nil
+
+	// 验证36位标准UUID格式（带连字符）
+	if len(uuid) == 36 && uuid[8] == '-' && uuid[13] == '-' && uuid[18] == '-' && uuid[23] == '-' {
+		// 检查除连字符外的字符是否为有效的十六进制
+		for i, c := range uuid {
+			if i == 8 || i == 13 || i == 18 || i == 23 {
+				continue // 跳过连字符位置
+			}
+			if !((c >= '0' && c <= '9') || (c >= 'a' && c <= 'f') || (c >= 'A' && c <= 'F')) {
+				return errors.New("UUID格式无效：包含非十六进制字符")
+			}
+		}
+		return nil
+	}
+
+	return errors.New("UUID格式无效：长度应为32位或36位")
 }
 
 // ValidateAccessToken 验证访问令牌