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/actions/admin-settings.ts

@@ -3,7 +3,7 @@
 import prisma from '@/lib/prisma'
 import { auth } from '@/auth'
 import { sendEmail } from '@/lib/mail'
-import { revalidateTag } from 'next/cache'
+import { updateTag } from 'next/cache'
 
 async function checkAdmin() {
   const session = await auth()
@@ -63,7 +63,7 @@ export async function updateSystemConfig(data: Record<string, string>) {
     await prisma.$transaction(operations)
 
     // Invalidate cache after update
-    revalidateTag('system-config')
+    updateTag('system-config')
 
     return { success: true }
   } catch (error) {