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- Fix sidebar: Notes nav no longer active on notebook pages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/components/sidebar.tsx

@@ -4,7 +4,7 @@ import Link from 'next/link'
 import { usePathname, useSearchParams, useRouter } from 'next/navigation'
 import { cn } from '@/lib/utils'
 import {
-  Lightbulb,
+  FileText,
   Bell,
   Archive,
   Trash2,
@@ -81,7 +81,8 @@ export function Sidebar({ className, user }: { className?: string, user?: any })
       return pathname === '/' &&
         !searchParams.get('label') &&
         !searchParams.get('archived') &&
-        !searchParams.get('trashed')
+        !searchParams.get('trashed') &&
+        !searchParams.get('notebook')
     }
 
     // For labels
@@ -131,7 +132,7 @@ export function Sidebar({ className, user }: { className?: string, user?: any })
       <div className="flex flex-col gap-1 px-3">
         <NavItem
           href="/"
-          icon={Lightbulb}
+          icon={FileText}
           label={t('sidebar.notes') || 'Notes'}
           active={isActive('/')}
         />