feat(KanbanFilters): add filter for hiding completed tasks older than 7 days

- Enhanced KanbanFilters component to include a new filter option for hiding tasks completed more than 15 days ago.
- Updated GeneralFilters component to display the new filter and its count.
- Modified TasksContext to calculate and provide the count of old completed tasks.
- Adjusted KanbanFiltersProps and related types to accommodate the new filter functionality.

src/lib/types.ts

@@ -85,6 +85,7 @@ export interface KanbanFilters {
   sortBy?: string;
   showWithDueDate?: boolean;
   showCompletedLast7Days?: boolean;
+  hideCompletedOlderThan15Days?: boolean;
   // Filtres spécifiques Jira
   showJiraOnly?: boolean;
   hideJiraTasks?: boolean;