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/providers-wrapper.tsx

@@ -1,11 +1,10 @@
 'use client'
 
 import { LanguageProvider, useLanguage } from '@/lib/i18n/LanguageProvider'
-import { LabelProvider } from '@/context/LabelContext'
 import { NotebooksProvider } from '@/context/notebooks-context'
-import { NotebookDragProvider } from '@/context/notebook-drag-context'
+import { EditorUIProvider } from '@/context/editor-ui-context'
 import { NoteRefreshProvider } from '@/context/NoteRefreshContext'
-import { HomeViewProvider } from '@/context/home-view-context'
+import { QueryProvider } from '@/components/query-provider'
 import type { ReactNode } from 'react'
 import type { Translations } from '@/lib/i18n/load-translations'
 
@@ -26,18 +25,18 @@ interface ProvidersWrapperProps {
 
 export function ProvidersWrapper({ children, initialLanguage = 'en', initialTranslations }: ProvidersWrapperProps) {
   return (
-    <NoteRefreshProvider>
-      <LabelProvider>
+    <QueryProvider>
+      <NoteRefreshProvider>
         <NotebooksProvider>
-          <NotebookDragProvider>
+          <EditorUIProvider>
             <LanguageProvider initialLanguage={initialLanguage as any} initialTranslations={initialTranslations}>
               <DirWrapper>
-                <HomeViewProvider>{children}</HomeViewProvider>
+                {children}
               </DirWrapper>
             </LanguageProvider>
-          </NotebookDragProvider>
+          </EditorUIProvider>
         </NotebooksProvider>
-      </LabelProvider>
-    </NoteRefreshProvider>
+      </NoteRefreshProvider>
+    </QueryProvider>
   )
 }