feat: smart note history with manual/auto modes, delete entries, i18n fixes

- Add noteHistoryMode setting (manual default / auto) with DB migration
- Manual mode: commit button in editor toolbar creates snapshots on demand
- Auto mode: smart snapshots with 20-char diff threshold + 5min cooldown,
  structural changes (color, pin, archive, labels) bypass cooldown
- Add delete individual history entries from history modal
- Fix sidebar: Notes nav no longer active on notebook pages
- Fix sidebar icon: replace filled Lightbulb with outlined FileText
- Fix title suggestions: change from amber to sky blue color scheme
- Fix hydration mismatch: add suppressHydrationWarning on locale dates
- Complete i18n: add history, sort, and AI chat translations for all 16 languages
- Translate French AI assistant section (40+ keys) from English to French
- Update README with new features and stack info

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

memento-note/app/(main)/page.tsx

@@ -21,6 +21,8 @@ export default async function HomePage() {
       initialSettings={{
         showRecentNotes: settings?.showRecentNotes !== false,
         notesViewMode,
+        noteHistory: settings?.noteHistory === true,
+        noteHistoryMode: (settings?.noteHistoryMode ?? 'manual') as 'manual' | 'auto',
       }}
     />
   )