refactor: split NoteEditor into focused components + consolidate contexts

Phase 1: NoteEditor Split (64KB → 9 focused components)
- components/note-editor/: types.ts, context, toolbar, title-block,
  content-area, metadata-section, full-page, dialog compositions
- Maintains backwards compatibility via re-export from note-editor.tsx

Phase 2: Context Consolidation (5 → 3 contexts)
- NotebooksContext absorbs LabelContext (labels CRUD)
- EditorUIContext merges HomeViewContext + NotebookDragContext
- Removed: LabelContext, home-view-context, notebook-drag-context

Phase 3: React Query Infrastructure
- Added QueryProvider with @tanstack/react-query
- lib/query-keys.ts: centralized query key definitions
- lib/query-hooks.ts: useNotes, useNotebooksQuery, useLabelsQuery
- lib/use-refresh.ts: hybrid invalidateQueries + triggerRefresh helper
- NotebooksContext: invalidateQueries on mutations (with triggerRefresh fallback)

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

memento-note/components/note-card.tsx

@@ -58,10 +58,9 @@ const ConnectionsOverlay = dynamic(() => import('./connections-overlay').then(m
 const ComparisonModal = dynamic(() => import('./comparison-modal').then(m => ({ default: m.ComparisonModal })), { ssr: false })
 const FusionModal = dynamic(() => import('./fusion-modal').then(m => ({ default: m.FusionModal })), { ssr: false })
 import { useConnectionsCompare } from '@/hooks/use-connections-compare'
-import { useLabels } from '@/context/LabelContext'
+import { useNotebooks } from '@/context/notebooks-context'
 import { useNoteRefresh } from '@/context/NoteRefreshContext'
 import { useLanguage } from '@/lib/i18n'
-import { useNotebooks } from '@/context/notebooks-context'
 import { toast } from 'sonner'
 
 // Mapping of supported languages to date-fns locales
@@ -172,11 +171,10 @@ export const NoteCard = memo(function NoteCard({
 }: NoteCardProps) {
   const router = useRouter()
   const searchParams = useSearchParams()
-  const { refreshLabels } = useLabels()
   const { triggerRefresh } = useNoteRefresh()
   const { data: session } = useSession()
   const { t, language } = useLanguage()
-  const { notebooks, moveNoteToNotebookOptimistic } = useNotebooks()
+  const { notebooks, moveNoteToNotebookOptimistic, refreshLabels } = useNotebooks()
   const [, startTransition] = useTransition()
   const [isDeleting, setIsDeleting] = useState(false)
   const [isHidden, setIsHidden] = useState(false)