feat: implement drag & drop functionality using @dnd-kit

- Added drag & drop capabilities to the Kanban board with @dnd-kit for task status updates.
- Integrated DndContext in `KanbanBoard` and utilized `useDroppable` in `KanbanColumn` for drop zones.
- Enhanced `TaskCard` with draggable features and visual feedback during dragging.
- Updated `TODO.md` to reflect the completion of drag & drop tasks and optimistically update task statuses.
- Introduced optimistic updates in `useTasks` for smoother user experience during drag & drop operations.

components/ui/HeaderContainer.tsx

@@ -1,8 +1,7 @@
 'use client';
 
-import { useState, useEffect } from 'react';
 import { Header } from './Header';
-import { tasksClient } from '@/clients/tasks-client';
+import { useTasks } from '@/hooks/useTasks';
 
 interface HeaderContainerProps {
   title: string;
@@ -17,41 +16,17 @@ interface HeaderContainerProps {
 }
 
 export function HeaderContainer({ title, subtitle, initialStats }: HeaderContainerProps) {
-  const [stats, setStats] = useState(initialStats);
-  const [isHydrated, setIsHydrated] = useState(false);
-
-  // Hydratation côté client
-  useEffect(() => {
-    setIsHydrated(true);
-  }, []);
-
-  // Rafraîchir les stats périodiquement côté client
-  useEffect(() => {
-    if (!isHydrated) return;
-
-    const refreshStats = async () => {
-      try {
-        const response = await tasksClient.getTasks({ limit: 1 }); // Juste pour les stats
-        setStats(response.stats);
-      } catch (error) {
-        console.error('Erreur lors du rafraîchissement des stats:', error);
-      }
-    };
-
-    // Rafraîchir les stats toutes les 30 secondes
-    const interval = setInterval(refreshStats, 30000);
-
-    // Rafraîchir immédiatement après hydratation
-    refreshStats();
-
-    return () => clearInterval(interval);
-  }, [isHydrated]);
+  const { stats, syncing } = useTasks(
+    { limit: 1 }, // Juste pour les stats
+    { tasks: [], stats: initialStats }
+  );
 
   return (
     <Header 
       title={title}
       subtitle={subtitle}
       stats={stats}
+      syncing={syncing}
     />
   );
 }