refactor(components): remove deprecated TaskDetailPanel re-export (#344)

Remove the backwards compatibility re-export file `TaskDetailPanel.tsx`
that was only re-exporting from `./task-detail/`. This file was unused -
the app imports directly from `./task-detail/TaskDetailModal`.

Removed:
- `src/renderer/components/TaskDetailPanel.tsx` - unused re-export file
- Export from `index.ts`

apps/frontend/src/renderer/components/TaskDetailPanel.tsx

@@ -1,3 +0,0 @@
-// Backwards compatibility re-export
-// This file has been refactored into smaller components in ./task-detail/
-export { TaskDetailPanel } from './task-detail';

apps/frontend/src/renderer/components/index.ts

@@ -2,7 +2,6 @@
 export * from './Sidebar';
 export * from './KanbanBoard';
 export * from './TaskCard';
-export * from './TaskDetailPanel';
 export * from './TaskCreationWizard';
 export * from './TaskEditDialog';
 export * from './AppSettings';