feat: 首次使用无检测通道时，仪表盘自动跳转到部署向导

internal/web/ui.go

@@ -913,6 +913,13 @@ func (u *UI) ensureDevicesLoaded() {
 }
 
 func (u *UI) pageDashboard(w http.ResponseWriter, r *http.Request) {
+    // First-time setup: if no recognition units exist, guide to wizard.
+    if u.preview != nil {
+        if units, err := u.preview.ListRecognitionUnits(); err == nil && len(units) == 0 {
+            http.Redirect(w, r, "/ui/wizard", http.StatusFound)
+            return
+        }
+    }
     data := u.deviceOverviewPageData(r, nil, "")
     if u.tasks != nil {
         for _, task := range u.tasks.ListTasks() {