## What changed
- Allow `start_or_steer_turn` to accept named `function_call_output` items without a `call_id`, starting a turn when idle or steering the active turn.
- Preserve standalone outputs as pending input, assign response item IDs, and record them in conversation history without treating them as user prompts.
## Testing
- Cover starting a turn with a standalone output and steering an active turn with one.
- Verify passive response items do not signal pending steering activity.
GitOrigin-RevId: e32b292106b3c5a5f03577b8ebf67d2d7dee4e5d