When switching between OpenAI models (e.g., gpt-5-mini to gpt-5.2-codex),
function_call IDs with fc_ prefix trigger pairing validation errors because
OpenAI tracks which fc_xxx IDs were paired with rs_xxx reasoning items.
The fix omits the id field for function_calls from different models, which
avoids the pairing validation while keeping call_id for matching with
function_call_output.
Fixes#886
Fixes OpenAI Responses 400 error 'reasoning without following item' by
skipping errored/aborted assistant messages entirely rather than filtering
at the provider level. This covers openai-responses, openai-codex-responses,
and future providers.
Removes strictResponsesPairing compat option (no longer needed).
Closes#838