FunctionCall log more verbose

When codex (Rust) calls a Tool (MCP), it logs "INFO FunctionCall: ..." in _.codex/log/codex-tui.log_
Example:
```
[2m2025-06-18T09:56:53.810843Z[0m [32m INFO[0m FunctionCall: {"project_root":"."}
```
It's not clear:

- Which tool of which MCP server has been called
- How long is this function call
- When it's terminated
- How to know when a Function Call is stuck and why (debugging)