fix: #3357 AgentOutputSchema.name() crash on Literal output types

[john-rocky]

Summary

AgentOutputSchema.name() previously crashed for any output type that contained typing.Literal, because _type_to_str recursed into each typing arg and unconditionally read __name__. The Literal value (e.g. the "ok" inside Literal["ok"]) is a str instance rather than a class, so the lookup raised AttributeError and broke the trace path when the run started. schema.json_schema() already worked, so the bug only surfaced at the very last step of agent setup.

The fix is local to _type_to_str:

• If the recursive arg isn't a class, fall back to repr(t) so literal values keep their original form ("'ok'", '1', etc.).
• Resolve origin names through getattr(origin, "__name__", None) or getattr(origin, "_name", None) or str(origin) so typing constructs that only expose _name (typing.Literal, typing.Union) still produce a readable label.

_type_to_str is now typed as t: Any to match the recursive call, which already passed non-type values into itself.

Test plan

Added test_structured_output_literal_name_does_not_crash covering:

• Literal["ok"] → "Literal['ok']" (the exact repro from the issue)
• Literal["ok", "done"] → "Literal['ok', 'done']"
• list[Literal["ok", "done"]] → "list[Literal['ok', 'done']]"
• Literal[1, 2] → "Literal[1, 2]"
• Plain types and existing generics (str, list[int]) unchanged

$ make format
All checks passed!
$ make lint
All checks passed!
$ uv run mypy src/agents/agent_output.py tests/test_output_tool.py
Success: no issues found in 2 source files
$ uv run pytest tests/test_output_tool.py -v
...
tests/test_output_tool.py::test_structured_output_literal_name_does_not_crash PASSED
============================== 12 passed in 0.11s ==============================

Issue number

Closes #3357.

Checks

• I've added new tests (if relevant)
• I've added/updated the relevant documentation
• I've run `make lint` and `make format`
• I've made sure tests pass

[seratch]

resolved by #3358