feat: icon-only toolbar, versioning fixes, history modal, PanelRight repositioning

- Toolbar: remove text labels from all icon buttons (AI, Save, Preview, Convert)
  all buttons now icon-only with title tooltip for accessibility
- Toolbar: reposition PanelRight (info panel toggle) to far right after three-dot menu
- Versioning: decouple getNoteHistory/restoreNoteVersion from global userAISettings.noteHistory
  now checks note.historyEnabled directly — unblocks manual per-note history
- Versioning: add 'Sauvegarder cette version' button in Versions tab of info panel
  calls commitNoteHistory with visual feedback (spinner → success state)
- note-document-info-panel: import commitNoteHistory, add isSavingVersion state
- notes.ts: fix double guard that silently blocked all history operations

memento-note/lib/types.ts

@@ -65,6 +65,8 @@ export interface Note {
   checkItems: CheckItem[] | null;
   labels: string[] | null;
   images: string[] | null;
+  /** SVG sanitisé pour vignette flux éditorial (ex. généré par IA) */
+  illustrationSvg?: string | null;
   links: LinkMetadata[] | null;
   reminder: Date | null;
   isReminderDone: boolean;