## Summary
- return typed `ToolOutput` values from the multi-agent handlers instead
of plain `FunctionToolOutput`
- keep the regular function-call response shape as JSON text while
exposing structured values to code mode
- add output schemas for `spawn_agent`, `send_input`, `resume_agent`,
`wait`, and `close_agent`
## Verification
- `just fmt`
- focused multi-agent and integration tests passed earlier in this
branch during iteration
- after the final edit, I only reran formatting before opening this PR
pakrym-oai
7626f61274