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)

internal/api/handler/sso_handler.go

@@ -12,25 +12,25 @@ import (
 
 // SSOHandler SSO 处理程序
 type SSOHandler struct {
-	ssoManager  *auth.SSOManager
+	ssoManager   *auth.SSOManager
 	clientsStore auth.SSOClientsStore
 }
 
 // NewSSOHandler 创建 SSO 处理程序
 func NewSSOHandler(ssoManager *auth.SSOManager, clientsStore auth.SSOClientsStore) *SSOHandler {
 	return &SSOHandler{
-		ssoManager:  ssoManager,
+		ssoManager:   ssoManager,
 		clientsStore: clientsStore,
 	}
 }
 
 // AuthorizeRequest 授权请求
 type AuthorizeRequest struct {
-	ClientID    string `form:"client_id" binding:"required"`
-	RedirectURI string `form:"redirect_uri" binding:"required"`
+	ClientID     string `form:"client_id" binding:"required"`
+	RedirectURI  string `form:"redirect_uri" binding:"required"`
 	ResponseType string `form:"response_type" binding:"required"`
-	Scope       string `form:"scope"`
-	State       string `form:"state"`
+	Scope        string `form:"scope"`
+	State        string `form:"state"`
 }
 
 // Authorize 处理 SSO 授权请求
@@ -220,17 +220,17 @@ func (h *SSOHandler) Token(c *gin.Context) {
 
 // IntrospectRequest Introspect 请求
 type IntrospectRequest struct {
-	Token  string `form:"token" binding:"required"`
+	Token    string `form:"token" binding:"required"`
 	ClientID string `form:"client_id"`
 }
 
 // IntrospectResponse Introspect 响应
 type IntrospectResponse struct {
-	Active   bool   `json:"active"`
-	UserID   int64  `json:"user_id,omitempty"`
-	Username string `json:"username,omitempty"`
-	ExpiresAt int64 `json:"exp,omitempty"`
-	Scope    string `json:"scope,omitempty"`
+	Active    bool   `json:"active"`
+	UserID    int64  `json:"user_id,omitempty"`
+	Username  string `json:"username,omitempty"`
+	ExpiresAt int64  `json:"exp,omitempty"`
+	Scope     string `json:"scope,omitempty"`
 }
 
 // Introspect 验证 access token