fix(audio): replace Mutex unwrap with poisoned-mutex recovery (TODO-006)

Replace 42 .lock().unwrap() calls with .unwrap_or_else(|e| e.into_inner())
across 7 files. Poisoned mutex recovery prevents panics in realtime audio
callbacks. Add SAFETY comment to WebRtcFallbackVad Send impl (TODO-007).

crates/chanora_audio/tests/ptt_privacy.rs

@@ -82,7 +82,7 @@ struct RecordingLayer {
 
 impl RecordingLayer {
     fn snapshot(&self) -> Vec<Captured> {
-        self.records.lock().unwrap().clone()
+        self.records.lock().unwrap_or_else(|e| e.into_inner()).clone()
     }
 }
 
@@ -118,7 +118,7 @@ where
             target: event.metadata().target().to_string(),
             field_names: names.0,
         };
-        self.records.lock().unwrap().push(captured);
+        self.records.lock().unwrap_or_else(|e| e.into_inner()).push(captured);
     }
 }