feat: RTL/i18n, AI translate+undo, no-refresh saves, settings perf

- RTL: force dir=rtl on LabelFilter, NotesViewToggle, LabelManagementDialog
- i18n: add missing keys (notifications, privacy, edit/preview, AI translate/undo)
- Settings pages: convert to Server Components (general, appearance) + loading skeleton
- AI menu: add Translate option (10 languages) + Undo AI button in toolbar
- Fix: saveInline uses REST API instead of Server Action → eliminates all implicit refreshes in list mode
- Fix: NotesTabsView notes sync effect preserves selected note on content changes
- Fix: auto-tag suggestions now filter already-assigned labels
- Fix: color change in card view uses local state (no refresh)
- Fix: nav links use <Link> for prefetching (Settings, Admin)
- Fix: suppress duplicate label suggestions already on note
- Route: add /api/ai/translate endpoint

keep-notes/components/notes-main-section.tsx

@@ -0,0 +1,43 @@
+'use client'
+
+import dynamic from 'next/dynamic'
+import { Note } from '@/lib/types'
+import { NotesTabsView } from '@/components/notes-tabs-view'
+
+const MasonryGridLazy = dynamic(
+  () => import('@/components/masonry-grid').then((m) => m.MasonryGrid),
+  {
+    ssr: false,
+    loading: () => (
+      <div
+        className="min-h-[200px] rounded-xl border border-dashed border-muted-foreground/20 bg-muted/30 animate-pulse"
+        aria-hidden
+      />
+    ),
+  }
+)
+
+export type NotesViewMode = 'masonry' | 'tabs'
+
+interface NotesMainSectionProps {
+  notes: Note[]
+  viewMode: NotesViewMode
+  onEdit?: (note: Note, readOnly?: boolean) => void
+  currentNotebookId?: string | null
+}
+
+export function NotesMainSection({ notes, viewMode, onEdit, currentNotebookId }: NotesMainSectionProps) {
+  if (viewMode === 'tabs') {
+    return (
+      <div className="flex min-h-0 flex-1 flex-col" data-testid="notes-grid-tabs-wrap">
+        <NotesTabsView notes={notes} onEdit={onEdit} currentNotebookId={currentNotebookId} />
+      </div>
+    )
+  }
+
+  return (
+    <div data-testid="notes-grid">
+      <MasonryGridLazy notes={notes} onEdit={onEdit} />
+    </div>
+  )
+}