perf(asgi): remove per-request fresh event-loop creation in bridge worker path #73

Context

ASGI bridge currently executes handle_rsgi via run_in_executor, and worker function uses asyncio.run(...) per request (fresh event loop per call). This adds fixed per-request overhead and executor churn under load.

Current code

• oxyroute/asgi.py: _run_handle_rsgi_blocking(...) + asyncio.run(_inner())

Goal

Reduce per-request overhead by avoiding fresh loop creation on every request in ASGI mode.

Candidate approaches

1. Long-lived worker thread with persistent loop.
2. Alternative bridge architecture that removes need for per-request asyncio.run.

Acceptance criteria

• ASGI bridge no longer creates a new loop per request.
• Stress test (tests/test_asgi_stress.py) remains green.
• Include before/after benchmark notes in PR description.

Notes

Keep behavior compatibility first; this is an internal perf refactor.