Exercises the patched default client_order + soft-fail DeobfData
end-to-end against current YouTube. Verifies:
1. iOS player_from_client returns streams (no deobf path).
2. TV player_from_client returns streams (deobf path with soft-fail).
3. default-clients player() picks iOS primary and a returned audio
URL HEADs to a 2xx/3xx (i.e. YouTube CDN accepts it).
Lives alongside the upstream tests/youtube.rs so we don't fork their
big snapshot-based test suite, but stays standalone so a single
`cargo test --test sulkta_smoke` exercises just the load-bearing
playback path for our consumers (straw, future torttube).
