[0xcadams]

What

Continue the Python wheel stack after #189: ensure ad-hoc URLs stop serving when their local ASGI listener exits unexpectedly, and verify the installed platform wheel can run a real local ASGI lifecycle.

Why

The Python SDK previously kept a ready URL registered after the listener had stopped, until the caller left the context manager. The wheel release check verified its binary and metadata but did not run a packaged ASGI app, and pull-request CI did not run Python checks or wheel packaging. Linux CI also exposed GoReleaser's valid seven-character snapshot IDs.

Changes

• Detect a stopped ASGI server, unregister its publisher before reporting a listener failure, and retry cleanup on close if necessary.
• Cover listener loss in the Python SDK tests.
• Run an installed-wheel ASGI startup, streaming HTTP, WebSocket, and shutdown smoke in platform wheel verification.
• Check the Python SDK and all platform wheels in CI, including seven-character GoReleaser snapshot IDs.