Mirror the core swap on the test side: every `Channel`/`Actor`
`.uid` access now reads the non-deprecated `.aid` struct's
`(.name, .uuid)` (or `.aid.name` for a `.uid[0]`), keeping the
compared / printed value byte-identical while silencing the
self-inflicted `DeprecationWarning`. Touches
`test_context_stream_semantics`, `test_spawning`, `test_local`,
`test_advanced_streaming`, `msg.test_ext_types_msgspec`,
`discovery.test_multi_program`, `test_infected_asyncio`.
(this patch was generated in some part by [`claude-code`][claude-code-gh])
[claude-code-gh]: https://github.com/anthropics/claude-code