feat: add objectstack-hooks skill for third-party developers

Agent-Logs-Url: https://github.com/objectstack-ai/framework/sessions/65fb3af8-127a-49b6-a200-29a63b6a8073

Co-authored-by: xuyushun441-sys <255036401+xuyushun441-sys@users.noreply.github.com>

Author: Claude