fix: use getTagsProvider for all auto-labeling paths, allow suggestions without notebook

- app/api/ai/tags/route.ts: getAIProvider → getTagsProvider (was using
  embedding model instead of tags model for legacy tag generation)
- lib/ai/services/auto-label-creation.service.ts: same fix
- hooks/use-auto-tagging.ts: remove notebookId gate that blocked all
  suggestions in "General Notes" — the API has a legacy path for this
- app/actions/admin-settings.ts: revalidateTag → updateTag (Next.js 16
  requires 2 args for revalidateTag)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

memento-note/app/api/ai/tags/route.ts

@@ -1,7 +1,7 @@
 import { NextRequest, NextResponse } from 'next/server';
 import { auth } from '@/auth';
 import { contextualAutoTagService } from '@/lib/ai/services/contextual-auto-tag.service';
-import { getAIProvider } from '@/lib/ai/factory';
+import { getTagsProvider } from '@/lib/ai/factory';
 import { getSystemConfig } from '@/lib/config';
 import { z } from 'zod';
 
@@ -44,7 +44,7 @@ export async function POST(req: NextRequest) {
 
     // Otherwise, use legacy auto-tagging (generates new tags)
     const config = await getSystemConfig();
-    const provider = getAIProvider(config);
+    const provider = getTagsProvider(config);
     const tags = await provider.generateTags(content, language);
 
     return NextResponse.json({ tags });