feat: add updatedAt field to AchievementCard and related services

- Introduced `updatedAt` property in `AchievementData`, `KeyAccomplishment`, and `Task` interfaces for improved task tracking.
- Updated `AchievementCard` UI to display the last updated date alongside completion date, enhancing user visibility.
- Adjusted `UIShowcaseClient` and `TasksService` to include `updatedAt` values, ensuring consistency across task management components.

src/components/ui-showcase/UIShowcaseClient.tsx

@@ -64,6 +64,7 @@ export function UIShowcaseClient() {
       description: 'Migration vers les composants UI génériques',
       impact: 'high',
       completedAt: new Date(),
+      updatedAt: new Date(),
       tags: ['refactoring', 'ui'],
       todosCount: 8
     },
@@ -73,6 +74,7 @@ export function UIShowcaseClient() {
       description: 'Ajout de 10 nouveaux thèmes avec CSS variables',
       impact: 'medium',
       completedAt: new Date(Date.now() - 86400000),
+      updatedAt: new Date(Date.now() - 86400000),
       tags: ['themes', 'css'],
       todosCount: 3
     }

src/components/ui/AchievementCard.tsx

@@ -12,6 +12,7 @@ export interface AchievementData {
   description?: string;
   impact: 'low' | 'medium' | 'high';
   completedAt: Date;
+  updatedAt: Date;
   tags?: string[];
   todosCount?: number;
 }
@@ -46,9 +47,12 @@ export function AchievementCard({
           </span>
           <PriorityBadge priority={achievement.impact} />
         </div>
-        <span className="text-xs text-[var(--muted-foreground)]">
-          {format(achievement.completedAt, 'dd/MM', { locale: fr })}
-        </span>
+        <div className="text-xs text-[var(--muted-foreground)] text-right">
+          <div>Terminé: {format(achievement.completedAt, 'dd/MM', { locale: fr })}</div>
+          {achievement.updatedAt && achievement.updatedAt.getTime() !== achievement.completedAt.getTime() && (
+            <div>Mis à jour: {format(achievement.updatedAt, 'dd/MM', { locale: fr })}</div>
+          )}
+        </div>
       </div>
       
       {/* Titre */}