feat: add pinned tag functionality and UI enhancements

- Introduced `isPinned` property to the `Tag` model for marking main objectives.
- Updated `TagForm` to include a checkbox for setting tags as pinned, enhancing user interaction.
- Enhanced `KanbanBoardContainer` to display pinned tasks in a dedicated `ObjectivesBoard`, improving task visibility.
- Modified `KanbanFilters` to support filtering by pinned tags, streamlining task management.
- Adjusted `TasksContext` to separate pinned tasks from regular tasks for better organization.

src/contexts/TasksContext.tsx

@@ -29,6 +29,7 @@ interface TasksContextType {
   kanbanFilters: KanbanFilters;
   setKanbanFilters: (filters: KanbanFilters) => void;
   filteredTasks: Task[];
+  pinnedTasks: Task[]; // Tâches avec tags épinglés (objectifs)
   // Tags
   tags: Tag[];
   tagsLoading: boolean;
@@ -54,9 +55,28 @@ export function TasksProvider({ children, initialTasks, initialStats }: TasksPro
   // État des filtres Kanban
   const [kanbanFilters, setKanbanFilters] = useState<KanbanFilters>({});
 
-  // Filtrage des tâches
+  // Séparer les tâches épinglées (objectifs) des autres
+  const { pinnedTasks, regularTasks } = useMemo(() => {
+    const pinnedTagNames = tags.filter(tag => tag.isPinned).map(tag => tag.name);
+    
+    const pinned: Task[] = [];
+    const regular: Task[] = [];
+    
+    tasksState.tasks.forEach(task => {
+      const hasPinnedTag = task.tags?.some(tagName => pinnedTagNames.includes(tagName));
+      if (hasPinnedTag) {
+        pinned.push(task);
+      } else {
+        regular.push(task);
+      }
+    });
+    
+    return { pinnedTasks: pinned, regularTasks: regular };
+  }, [tasksState.tasks, tags]);
+
+  // Filtrage des tâches régulières (pas les épinglées)
   const filteredTasks = useMemo(() => {
-    let filtered = tasksState.tasks;
+    let filtered = regularTasks;
 
     // Filtre par recherche
     if (kanbanFilters.search) {
@@ -85,7 +105,7 @@ export function TasksProvider({ children, initialTasks, initialStats }: TasksPro
     }
 
     return filtered;
-  }, [tasksState.tasks, kanbanFilters]);
+  }, [regularTasks, kanbanFilters]);
 
   const contextValue: TasksContextType = {
     ...tasksState,
@@ -94,7 +114,8 @@ export function TasksProvider({ children, initialTasks, initialStats }: TasksPro
     tagsError,
     kanbanFilters,
     setKanbanFilters,
-    filteredTasks
+    filteredTasks,
+    pinnedTasks
   };
 
   return (