feat: add backlog status and update task stats

- Introduced 'backlog' status in TaskStatus type and STATUS_CONFIG for better task categorization.
- Updated TaskStats interface to include backlog count.
- Enhanced getTaskStats method to fetch backlog statistics and display in Header component.
- Added backlog stat card in Header for improved visibility of task status.

services/tasks.ts

@@ -189,13 +189,15 @@ export class TasksService {
    * Récupère les statistiques des tâches
    */
   async getTaskStats() {
-    const [total, completed, inProgress, todo, cancelled, freeze] = await Promise.all([
+    const [total, completed, inProgress, todo, backlog, cancelled, freeze, archived] = await Promise.all([
       prisma.task.count(),
       prisma.task.count({ where: { status: 'done' } }),
       prisma.task.count({ where: { status: 'in_progress' } }),
       prisma.task.count({ where: { status: 'todo' } }),
+      prisma.task.count({ where: { status: 'backlog' } }),
       prisma.task.count({ where: { status: 'cancelled' } }),
-      prisma.task.count({ where: { status: 'freeze' } })
+      prisma.task.count({ where: { status: 'freeze' } }),
+      prisma.task.count({ where: { status: 'archived' } })
     ]);
 
     return {
@@ -203,8 +205,10 @@ export class TasksService {
       completed,
       inProgress,
       todo,
+      backlog,
       cancelled,
       freeze,
+      archived,
       completionRate: total > 0 ? Math.round((completed / total) * 100) : 0
     };
   }