Add project selector in task detail, archive completed tasks

src/pages/Project.tsx

@@ -5,6 +5,7 @@ import { cn } from '@/lib/utils';
 import { useTasksStore } from '@/stores/tasks';
 import { TaskItem } from '@/components/TaskItem';
 import { AddTask } from '@/components/AddTask';
+import { CompletedSection } from '@/components/CompletedSection';
 import { BoardView } from '@/pages/Board';
 import { api } from '@/lib/api';
 import type { Project as ProjectType, Section } from '@/types';
@@ -13,7 +14,7 @@ export function ProjectPage() {
   const { id } = useParams<{ id: string }>();
   const location = useLocation();
   const navigate = useNavigate();
-  const { tasks, isLoading, fetchTasks, setSelectedTask } = useTasksStore();
+  const { tasks, completedTasks, isLoading, fetchTasks, fetchCompletedTasks, setSelectedTask } = useTasksStore();
   const [project, setProject] = useState<ProjectType | null>(null);
   const [sections, setSections] = useState<Section[]>([]);
   
@@ -22,6 +23,7 @@ export function ProjectPage() {
   useEffect(() => {
     if (!id) return;
     fetchTasks({ projectId: id, completed: false });
+    fetchCompletedTasks({ projectId: id });
     api.getProject(id).then((p) => {
       setProject(p);
       setSections(p.sections || []);
@@ -138,6 +140,9 @@ export function ProjectPage() {
                   <AddTask projectId={id} sectionId={section.id} />
                 </div>
               ))}
+
+              {/* Completed tasks */}
+              <CompletedSection tasks={completedTasks} />
             </>
           )}
         </div>