merge(audio): land feat/linux-stream-sink — Linux host-owned stream sink

Merges 44b71e74 (see its message for the full design: the "Punktfunk Stream
Speaker" Audio/Sink claimed as the session's default output — the crackle
root fix for hardware-sink churn — plus the core-error liveness fix and true
5.1/7.1 capture) across the W1–W8 refactor that landed since the branch
forked:

- punktfunk1.rs was split on main: the audio_thread idle()/drain() hunks are
  hand-ported into native/audio.rs (same three sites: reuse-drain comment,
  encoder-fail park, end-of-thread park).
- pwinit moved to pf-capture (W6.2): the branch's crate::pwinit calls in
  pw_thread and stream_sink.rs become pf_capture::pwinit.
- Kept main's log-tier demotions (stream-state + setup lines at debug)
  inside the restructured pw_thread.

Resolution verified on Linux (home-worker-5): clippy -D warnings clean +
173 punktfunk-host tests green at the 691c064a-based equivalent ba5973a2;
re-verified at this base before landing.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

crates/punktfunk-host/src/gamestream/audio.rs

@@ -297,6 +297,7 @@ fn run(
         None => audio::open_audio_capture(want).context("open audio capture")?,
     };
     let result = audio_body(&mut *cap, &sock, gcm_key, rikeyid, params, running);
+    cap.idle(); // parked between sessions — release the routing claim (Linux stream sink)
     *audio_cap.lock().unwrap() = Some(cap);
     result
 }