fix(audio): poll only the default device when none is pinned (#996) (#1039)

* fix(audio): poll only the default device when none is pinned (#996)

The device watcher ran a full output_devices() + per-device description()
CoreAudio enumeration every 3s, even with no pinned device. On some macOS
setups this contends with the audio render thread and causes a brief dropout
once per poll — a stutter whose cadence tracks the poll interval exactly.

The full enumeration is only needed to detect a pinned device disappearing.
With no pin (system default, the common case) only the current default is
needed, so the enumeration is skipped entirely in that case; the cheap
single default_output_device() query still detects default-device changes.

Confirmed with a diagnostic build: throttling the enumeration to ~60s moved
the reporter's stutter cadence from ~3s to ~60s, isolating the enumeration
as the cause.

* docs: add CHANGELOG entry for PR #1039

CHANGELOG.md

@@ -167,6 +167,14 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 
 
+### Playback — macOS stutter from background device checks
+
+**By [@Psychotoxical](https://github.com/Psychotoxical), PR [#1039](https://github.com/Psychotoxical/psysonic/pull/1039)**
+
+* On some macOS setups playback stuttered at a steady ~3-second cadence: a background check that scans every audio output device ran on each poll and briefly contended with playback. It now runs only when a specific output device is pinned; with the system default (the common case) a single lightweight check runs instead.
+
+
+
 ### Track preview — Symphonia 0.6 format hints and fast stream start
 
 **By [@cucadmuh](https://github.com/cucadmuh), PR [#1006](https://github.com/Psychotoxical/psysonic/pull/1006)**