Promotes the complete OFFSEC-003 boundary-marker sanitization from staging
to main, including:
- _delegate_sync_via_polling: sanitize response_preview and error strings
before returning (OFFSEC-003 polling-path fix from PR #417).
- tool_check_task_status JSON endpoint: sanitize summary + response_preview
in both the task_id filter path and the list path.
- tool_delegate_task non-polling path: preserve main's existing
sanitize_a2a_result(result) wrapper (staging accidentally removed it).
Closes#418.
Co-Authored-By: Molecule AI · core-be <core-be@agents.moleculesai.app>