test: add comprehensive test coverage and improve code quality

- Add new test files for auth, service, and handler modules
- Improve test organization and coverage
- Refactor code for better maintainability
- Add captcha, settings, stats, and theme handler tests
- Add auth module tests (CAS, OAuth, password, SSO, state)
- Add service layer tests for auth, export, permissions, roles
- All Go tests pass (exit code 0)
- All frontend tests pass (325 tests in 59 files)

pkg/errors/errors.go

@@ -7,7 +7,7 @@ import (
 
 var (
 	// 用户相关错误
-	ErrUserNotFound      = errors.New("用户不存在")
+	ErrUserNotFound       = errors.New("用户不存在")
 	ErrUsernameExists     = errors.New("用户名已存在")
 	ErrEmailExists        = errors.New("邮箱已存在")
 	ErrPhoneExists        = errors.New("手机号已存在")
@@ -17,20 +17,20 @@ var (
 	ErrInvalidOldPassword = errors.New("原密码错误")
 
 	// 角色相关错误
-	ErrRoleNotFound          = errors.New("角色不存在")
-	ErrRoleCodeExists       = errors.New("角色代码已存在")
+	ErrRoleNotFound           = errors.New("角色不存在")
+	ErrRoleCodeExists         = errors.New("角色代码已存在")
 	ErrCannotModifySystemRole = errors.New("不能修改系统角色")
 	ErrCannotDeleteSystemRole = errors.New("不能删除系统角色")
-	ErrRoleInUse            = errors.New("角色正在使用中")
+	ErrRoleInUse              = errors.New("角色正在使用中")
 
 	// 权限相关错误
 	ErrPermissionNotFound   = errors.New("权限不存在")
 	ErrPermissionCodeExists = errors.New("权限代码已存在")
 
 	// 通用错误
-	ErrInvalidParams  = errors.New("参数错误")
-	ErrUnauthorized   = errors.New("未授权")
-	ErrForbidden      = errors.New("无权限")
+	ErrInvalidParams       = errors.New("参数错误")
+	ErrUnauthorized        = errors.New("未授权")
+	ErrForbidden           = errors.New("无权限")
 	ErrInternalServerError = errors.New("服务器内部错误")
 )