fix(task): append plan delegation prompt requirements

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

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

src/tools/delegate-task/index.ts

@@ -1,4 +1,4 @@
-export { createDelegateTask, resolveCategoryConfig, buildSystemContent } from "./tools"
+export { createDelegateTask, resolveCategoryConfig, buildSystemContent, buildTaskPrompt } from "./tools"
 export type { DelegateTaskToolOptions, SyncSessionCreatedEvent, BuildSystemContentInput } from "./tools"
 export type * from "./types"
 export * from "./constants"