Summary

Adds smoke coverage for one more self-contained docs snippet in tests/test_docs_examples_verified.py.

What changed

• added a smoke test for docs/snippets/decorator_retry.py
• stubbed sync and async sleep paths so the snippet runs quickly and locally
• asserted the expected sync-ok and async-ok output

Why

This expands the set of visibly verified docs examples and improves confidence in the snippets.

Verification

• uv run pytest -o addopts="" tests/test_docs_examples_verified.py -k decorator_retry
• full file also passes once the existing pyperf dev dependency is available for bench_retry.py