fix(security): validate auth file names to prevent unsafe input

internal/api/handlers/management/auth_files_download_windows_test.go

@@ -0,0 +1,51 @@
+//go:build windows
+
+package management
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"net/url"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/gin-gonic/gin"
+	"github.com/router-for-me/CLIProxyAPI/v6/internal/config"
+)
+
+func TestDownloadAuthFile_PreventsWindowsSlashTraversal(t *testing.T) {
+	t.Setenv("MANAGEMENT_PASSWORD", "")
+	gin.SetMode(gin.TestMode)
+
+	tempDir := t.TempDir()
+	authDir := filepath.Join(tempDir, "auth")
+	externalDir := filepath.Join(tempDir, "external")
+	if err := os.MkdirAll(authDir, 0o700); err != nil {
+		t.Fatalf("failed to create auth dir: %v", err)
+	}
+	if err := os.MkdirAll(externalDir, 0o700); err != nil {
+		t.Fatalf("failed to create external dir: %v", err)
+	}
+
+	secretName := "secret.json"
+	secretPath := filepath.Join(externalDir, secretName)
+	if err := os.WriteFile(secretPath, []byte(`{"secret":true}`), 0o600); err != nil {
+		t.Fatalf("failed to write external file: %v", err)
+	}
+
+	h := NewHandlerWithoutConfigFilePath(&config.Config{AuthDir: authDir}, nil)
+
+	rec := httptest.NewRecorder()
+	ctx, _ := gin.CreateTestContext(rec)
+	ctx.Request = httptest.NewRequest(
+		http.MethodGet,
+		"/v0/management/auth-files/download?name="+url.QueryEscape("../external/"+secretName),
+		nil,
+	)
+	h.DownloadAuthFile(ctx)
+
+	if rec.Code != http.StatusBadRequest {
+		t.Fatalf("expected status %d, got %d with body %s", http.StatusBadRequest, rec.Code, rec.Body.String())
+	}
+}