Fix race-audio Test buttons silently saving settings to the database

Clicking a Test button (general or per-event) in the race-sounds table
called persistRaceAudioFormValues, which both applied the form's
current values and saved them to the backend on every click. A sound
preview should only apply values in memory, not persist them - split
into an apply-only helper used by the Test buttons, keeping the
existing save behavior for the explicit Save button and field changes.

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

package.json

@@ -1,6 +1,6 @@
 {
   "name": "rc-racecore",
-  "version": "1.12.0",
+  "version": "1.12.1",
   "private": true,
   "description": "RC RaceCore live timing and race control with AMMC ingest and SQLite persistence",
   "engines": {