fix(web): stop board swaps from nesting the full board inside the grid

Status-change actions (detail panel buttons and drag-and-drop) targeted
#kanban-board with innerHTML, but the handlers return the full
_KanbanBoard partial including the #board-content wrapper and filter
bar. Each action nested a new board inside the grid, duplicating the
filter chips and collapsing the layout. Target #board-content with
outerHTML instead, matching the filter bar and create-task form.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

TaskTracker.Api/wwwroot/js/app.js

@@ -47,8 +47,8 @@
 
                     // Fire htmx request to update the task status
                     htmx.ajax('PUT', '/board?handler=' + handler + '&id=' + taskId, {
-                        target: '#kanban-board',
-                        swap: 'innerHTML'
+                        target: '#board-content',
+                        swap: 'outerHTML'
                     });
                 }
             });