fix(health): correct preset-count guidance, drop wrong citation

The speaker_presets_count check told users a power-cycle "usually
re-syncs" missing presets. #614 shows a power-cycle is itself one of
the two reported triggers for the speaker wiping its own presets, so
that advice was actively harmful for this failure mode.

Also fixes the comment's citation: it claimed this was a known pattern
from discussion #295 and #235, but neither actually discusses preset
loss (#295 is a cloud-hosting question, #235 a closed Spotify
preset-save bug). That reference was wrong from the original commit
(7d46ae2); #614 is the first confirmed instance.

Refs #614

pkg/service/health/checks_presets_count.go

@@ -129,8 +129,9 @@ func comparePresetsForDeviceWithURL(ds *datastore.DataStore, account, deviceID,
 	severity := SeverityInfo
 	if speakerCount == 0 && serviceCount > 0 {
 		// Speaker shows nothing while the service has presets —
-		// this is the post-reset preset-loss class from
-		// discussion #295 and #235.
+		// the post-reset preset-loss pattern confirmed in #614
+		// (reboot and/or Sync leaving the speaker's own preset
+		// slots empty while the service's Presets.xml is untouched).
 		severity = SeverityWarning
 	}
 
@@ -141,7 +142,7 @@ func comparePresetsForDeviceWithURL(ds *datastore.DataStore, account, deviceID,
 			"Speaker shows %d preset slot(s); service Presets.xml has %d.",
 			speakerCount, serviceCount,
 		),
-		Details: "If the speaker shows fewer than the service, a power-cycle or a sourcesUpdated notification usually re-syncs. If it shows more, the service may have stale entries or the speaker is still holding pre-migration state.",
+		Details: "If the speaker shows fewer than the service, a sourcesUpdated notification sometimes re-syncs it. Don't power-cycle as a fix for this — it has itself been reported to wipe the speaker's presets (#614), so it may make things worse. If the speaker shows more than the service, the service may have stale entries or the speaker is still holding pre-migration state.",
 	}}
 }