fix(delegate-task): propagate category in background continuation

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

src/tools/delegate-task/background-continuation.ts

@@ -36,6 +36,7 @@ export async function executeBackgroundContinuation(
       metadata: {
         prompt: args.prompt,
         agent: task.agent,
+        ...(task.category !== undefined ? { category: task.category } : {}),
         load_skills: args.load_skills,
         description: args.description,
         run_in_background: args.run_in_background,