Level A of issue #307 was firing 'device no longer available' spuriously
because settings.output_device stores the ALSA-normalized form
(front:CARD=X,DEV=0 per normalize_device_id_to_stable) while cpal's
output_devices() enumeration returns different strings entirely —
DeviceTrait::description() (friendly) and DeviceTrait::name() both
produce values that don't match what the UI persisted. Comparing them
marked every configured device as 'missing' on normal playback.
Removes the pre-flight emit_missing_if_needed() calls from
v2_play_track and v2_resume_playback so the false-positive toast
stops firing. The init_device fallback still routes audio to default
on a truly missing device — we just no longer surface that to the UI,
which is net neutral for the user vs. wrong notifications.
Keeps audio_device_watch module, DeviceMissingThrottle state and the
frontend listener in place so Level B (emit from inside the audio
thread when the fallback actually triggers) can reuse the plumbing
without another refactor. Hardens the presence check with
empty-enumeration = inconclusive and description()-based matching for
whenever Level B actually wires up a call site that has a comparable
device name at hand.
cc
vicrodh
f7e51b980e