feat(HAI-043): fix title fallback to show description instead of duplicate ID

- Update TaskCard and TaskDetailModal to display description as fallback instead of repeating the task ID
- Remove unused hooks (useFlashOnIncrease), routes, assets, and dead CSS
- Clean up engine modules (executor, scheduler, triage, worktree-names) removing unused code
- Update and add tests for title fallback behavior in TaskDetailModal
- Fix pre-existing type error in test helper (types.ts)

packages/dashboard/app/components/TaskDetailModal.tsx

@@ -158,7 +158,7 @@ export function TaskDetailModal({
           </button>
         </div>
         <div className="detail-body">
-          <h2 className="detail-title">{task.title || task.id}</h2>
+          <h2 className="detail-title">{task.title || task.description}</h2>
           <div className="detail-meta">
             Created {new Date(task.createdAt).toLocaleDateString()} · Updated{" "}
             {new Date(task.updatedAt).toLocaleDateString()}