Agents can now call external tools (GitHub, Slack, Gmail, etc.) via
Composio's managed API. A thin HTTP client calls the Composio REST API
directly — no heavy SDK dependency. External tools are loaded per-org
from composio_settings and merged with internal tools at run time. The
agent run loop routes composio_* tool calls to the Composio execution
endpoint while internal tools dispatch as before.
Includes: migration 043 for composio_settings table, IPC handler for
saving Composio API key and toolkit configuration, and the composio
client/bridge modules.