feat: update dashboard components and analytics for 7-day summaries

- Modified `ManagerWeeklySummary`, `MetricsTab`, and `ProductivityAnalytics` to reflect a focus on the last 7 days instead of the current week.
- Enhanced `ManagerSummaryService` and `MetricsService` to calculate metrics over a sliding 7-day window, improving data relevance.
- Added a new utility function `formatDistanceToNow` for better date formatting in French.
- Updated comments and documentation to clarify changes in timeframes.

src/components/dashboard/ManagerWeeklySummary.tsx

@@ -27,7 +27,7 @@ export default function ManagerWeeklySummary({ initialSummary }: ManagerWeeklySu
 
 
   const formatPeriod = () => {
-    return `Semaine du ${format(summary.period.start, 'dd MMM', { locale: fr })} au ${format(summary.period.end, 'dd MMM yyyy', { locale: fr })}`;
+    return `7 derniers jours (${format(summary.period.start, 'dd MMM', { locale: fr })} - ${format(summary.period.end, 'dd MMM yyyy', { locale: fr })})`;
   };
 
   const getPriorityBadgeStyle = (priority: 'low' | 'medium' | 'high') => {
@@ -134,7 +134,7 @@ export default function ManagerWeeklySummary({ initialSummary }: ManagerWeeklySu
               </div>
               
               <div className="bg-green-50 p-4 rounded-lg border-l-4 border-green-400">
-                <h3 className="font-medium text-green-900 mb-2">🔮 Focus semaine prochaine</h3>
+                <h3 className="font-medium text-green-900 mb-2">🔮 Focus 7 prochains jours</h3>
                 <p className="text-green-800">{summary.narrative.nextWeekFocus}</p>
               </div>
             </CardContent>
@@ -346,7 +346,7 @@ export default function ManagerWeeklySummary({ initialSummary }: ManagerWeeklySu
       {activeView === 'accomplishments' && (
         <Card>
           <CardHeader>
-            <h2 className="text-lg font-semibold">✅ Accomplissements de la semaine</h2>
+            <h2 className="text-lg font-semibold">✅ Accomplissements des 7 derniers jours</h2>
             <p className="text-sm text-[var(--muted-foreground)]">
               {summary.keyAccomplishments.length} accomplissements significatifs • {summary.metrics.totalTasksCompleted} tâches • {summary.metrics.totalCheckboxesCompleted} todos complétés
             </p>