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/lib/i18n/load-translations.ts

@@ -41,6 +41,8 @@ export interface Translations {
     editLabels: string
     archive: string
     trash: string
+    newNoteTabs: string
+    newNoteTabsHint: string
   }
   notes: {
     title: string
@@ -103,6 +105,7 @@ export interface Translations {
     noNotes: string
     noNotesFound: string
     createFirstNote: string
+    emptyStateTabs: string
     size: string
     small: string
     medium: string
@@ -126,6 +129,12 @@ export interface Translations {
     markdownOff: string
     undo: string
     redo: string
+    viewCards: string
+    viewTabs: string
+    viewCardsTooltip: string
+    viewTabsTooltip: string
+    viewModeGroup: string
+    reorderTabs: string
   }
   pagination: {
     previous: string
@@ -782,6 +791,10 @@ export interface Translations {
   appearance: {
     title: string
     description: string
+    notesViewDescription: string
+    notesViewLabel: string
+    notesViewTabs: string
+    notesViewMasonry: string
   }
   generalSettings: {
     title: string