feat: improve AI Chat UX, add notebook summary, and fix shared/reminders routing

memento-note/app/(main)/settings/general/general-settings-client.tsx

@@ -29,9 +29,11 @@ export function GeneralSettingsClient({ initialSettings }: GeneralSettingsClient
     await updateAISettings({ preferredLanguage: value as any })
     if (value === 'auto') {
       localStorage.removeItem('user-language')
+      document.cookie = 'user-language=;path=/;max-age=0'
       toast.success(t('settings.languageAuto') || 'Language set to Auto')
     } else {
       localStorage.setItem('user-language', value)
+      document.cookie = `user-language=${value};path=/;max-age=${60 * 60 * 24 * 365};samesite=lax`
       setContextLanguage(value as any)
       toast.success(t('profile.languageUpdateSuccess') || 'Language updated')
     }