feat(typebot): add MEGA_CMD, list placeholders, and agent/team assignment docs

- Add MEGA_CMD section: local command interception for agent/team
  assignment without webhooks
- Add list placeholders section: [TEAMS_LIST] and [AGENTS_LIST]
  dynamic numbered menus for WhatsApp
- Add markdown list escaping documentation (ZWS approach)
- Add bot token API access section (agents, teams, contacts)
- Update prefilled variables: agents_json, teams_json, agents_formatted,
  teams_formatted
- Add example flow JSON for agent/team assignment workflow
- All changes in en, es, and pt-br