feat(skills): flag unmanaged skills with a green dot on the Import button

- Add an optional `enabled` flag to useScanUnmanagedSkills; the Skills panel
  scans once on mount (enabled:true), with 30s staleTime + keepPreviousData to
  dedupe disk IO across navigations.
- App subscribes to the shared query (enabled:false) and renders a green dot +
  tooltip on the top-bar Import button when unmanaged skills are available.

src/App.tsx

@@ -46,6 +46,7 @@ import { useAutoCompact } from "@/hooks/useAutoCompact";
 import { useUsageCacheBridge } from "@/hooks/useUsageCacheBridge";
 import { useTauriEvent } from "@/hooks/useTauriEvent";
 import { useLastValidValue } from "@/hooks/useLastValidValue";
+import { useScanUnmanagedSkills } from "@/hooks/useSkills";
 import { extractErrorMessage } from "@/utils/errorUtils";
 import { isTextEditableTarget } from "@/utils/domUtils";
 import { deepClone } from "@/utils/deepClone";
@@ -250,6 +251,10 @@ function App() {
   const mcpPanelRef = useRef<any>(null);
   const skillsPageRef = useRef<any>(null);
   const unifiedSkillsPanelRef = useRef<any>(null);
+  // 订阅未管理 Skill 的共享缓存（实际扫描由 UnifiedSkillsPanel 进入页面时触发）。
+  // 这里 enabled 默认 false，仅用于「导入」按钮的绿点提示，不主动发起扫描。
+  const { data: unmanagedSkills } = useScanUnmanagedSkills();
+  const hasUnmanagedSkills = (unmanagedSkills?.length ?? 0) > 0;
   const addActionButtonClass =
     "bg-orange-500 hover:bg-orange-600 dark:bg-orange-500 dark:hover:bg-orange-600 text-white shadow-lg shadow-orange-500/30 dark:shadow-orange-500/40 rounded-full w-8 h-8";
 
@@ -1315,10 +1320,21 @@ function App() {
                       onClick={() =>
                         unifiedSkillsPanelRef.current?.openImport()
                       }
-                      className="hover:bg-black/5 dark:hover:bg-white/5"
+                      className="relative hover:bg-black/5 dark:hover:bg-white/5"
+                      title={
+                        hasUnmanagedSkills
+                          ? t("skills.unmanagedAvailable")
+                          : undefined
+                      }
                     >
                       <Download className="w-4 h-4 mr-2" />
                       {t("skills.import")}
+                      {hasUnmanagedSkills && (
+                        <span
+                          className="absolute top-1 right-1 h-2 w-2 rounded-full bg-green-500"
+                          aria-hidden="true"
+                        />
+                      )}
                     </Button>
                     <Button
                       variant="ghost"