docs: document auto_previous_response_id

[ioleksiuk]

Summary

Two pieces of doc drift accumulated in the public `Runner` methods:

• PR Enable previous_response_id chaining for internal calls on the first turn #2117 added the `auto_previous_response_id` parameter to `Runner.run`, `Runner.run_sync`, and `Runner.run_streamed` signatures but did not document it in the `Args:` blocks (parameter appears in `inspect.signature` but not in `inspect.getdoc`).
• PR fix: #3055 surface model refusals during run resolution #3057 added `model_refusal` as a supported key in `RunErrorHandlers`, but four `error_handlers:` docstrings still claim "Currently supports max_turns" only (three in `run.py` plus `RunOptions.error_handlers` in `run_config.py`).

This PR adds the missing `auto_previous_response_id` entry to each `Args:` block and updates the `error_handlers` description to list both handler kinds.

Test plan

```
$ uv run python -c "
import inspect
from agents import Runner
for name in ('run', 'run_sync', 'run_streamed'):
doc = inspect.getdoc(getattr(Runner, name)) or ''
print(name, 'auto_previous_response_id:', 'auto_previous_response_id' in doc,
'model_refusal:', 'model_refusal' in doc)
"
run auto_previous_response_id: True model_refusal: True
run_sync auto_previous_response_id: True model_refusal: True
run_streamed auto_previous_response_id: True model_refusal: True
```

• `uv run ruff check src/agents/run.py src/agents/run_config.py` — All checks passed.
• Docs-only change; no runtime tests apply.

Issue number

N/A — found during a docstring/signature drift audit following recent param/handler additions.

Checks

• I've added new tests (if relevant) — docs only, no test changes
• I've added/updated the relevant documentation
• I've run `make lint` and `make format`
• I've made sure tests pass

[seratch]

We'd like to have only the auto_previous_response_id documentation

[ioleksiuk]

Thanks for the review! Updated to address both comments:

• Dropped the Currently supports ... enumeration from all four error_handlers docstrings (3 in run.py, 1 in run_config.py). The line now reads just error_handlers: Error handlers keyed by error kind. — no list to fall out of date.
• auto_previous_response_id documentation kept in all three Runner methods (unchanged from the previous push).

Rebased onto latest main and force-pushed.