Multi-turn tool calls collided on replay: the reducer regenerated call_0,
call_1, ... every turn while ignoring the API's real call ids, so replayed
history had duplicate function_call/function_call_output ids that the API
cannot pair (visible once a conversation has two tool-using turns).
- ProviderEventReducer::tool_call_start_with_id(index, name, id) keeps the
API's id; tool_call_start delegates with an auto-generated fallback
- Responses API: use item.call_id; Chat Completions: use tool_calls[].id
- regressions: real-log test asserts the captured ids, agent replay test
asserts ids stay unique across three turns; reducer id-override test
DaiChaoXiong