Description

When integrating the SDK into async deployment pipelines, transient network blips or underlying cloud provider 50X errors cause hard crashes. This PR introduces a configurable max_retries parameter (default: 3) to the Proofline client, leveraging httpx native HTTPTransport and AsyncHTTPTransport retry mechanics to improve resiliency out-of-the-box.

Implementation Details

• Added max_retries to client initialization.
• Injected httpx.HTTPTransport(retries=max_retries) and httpx.AsyncHTTPTransport(retries=max_retries).
• Added mock tests in tests/ verifying retry execution on 503 responses.

Testing Notes & CI Baseline

• Pytest: pytest passes. Note: test_body_stream_deadline_does_not_turn_authority_into_timeout exhibited flakiness (timing sensitivity), but this behavior is pre-existing on main.
• Ruff: ruff check . passes cleanly.
• Mypy: The new implementation and tests type-check cleanly. Note: mypy . surfaces 5 pre-existing errors in tests/test_http.py on main, as the local scripts/check.py gate currently only targets proofline and scripts.