fix: SF2 sound (audio sink FIFO underrun) + VST3 native GUI open + GUI load race

- bridgeAudioNode: ScriptProcessor 4096 drained only 1 of 16 blocks -> ~94% silence; now drains all queued blocks per callback, RING_DEPTH 8->24
- app.jsx: openNativeGUI had NO caller; wire after VST3 loadInstrument OK in track Synth dropdown + Plugin Manager Load Bridge
- main.cpp: OPEN_GUI polls up to 10s for LOAD completion (worker thread) before attach - fixes race 'no instrument loaded'
- index.html: bump bridgeAudioNode/app.precompiled cache versions

app/templates/index.html

@@ -40,7 +40,7 @@
     <script src="/static/js/services/soundfontStorage.js?v=202607271016"></script>
     <script src="/static/js/services/soundfontPlayer.js?v=202608101800"></script>
     <script src="/static/js/services/nativeBridgeService.js?v=202608112200"></script>
-    <script src="/static/js/services/bridgeAudioNode.js?v=202608112200"></script>
+    <script src="/static/js/services/bridgeAudioNode.js?v=202608121600"></script>
     <script src="/static/js/services/unifiedMidiRouter.js?v=202608112200"></script>
     <script src="/static/js/services/audioRoutingEngine.js?v=202608112200"></script>
     <script src="/static/js/services/aiGateway.js?v=202608037200"></script>
@@ -50,7 +50,7 @@
     <script src="/static/js/services/midiExtractor.js?v=202607281052"></script>
     <script src="/static/js/services/promptTemplateManager.js?v=202607281039"></script>
     <script src="/static/js/services/undoRedoEngine.js?v=202607290941"></script>
-    <script src="/static/js/app.precompiled.js?v=202608121215" defer></script>
+    <script src="/static/js/app.precompiled.js?v=202608121600" defer></script>
     <link rel="stylesheet" href="/static/css/styles.css?v=202607271016">
     <style>
         :root {