fix(v8): 5 bugs — orphan bridge watchdog+state overwrite, stuck-note stop race, white VST GUI retry, VSTi auto-load via saved plugin_path, track-header button overflow

- native bridge: dedicated watchdog thread (parent death / PID-reuse via GetProcessTimes) -> TerminateProcess self; transportStopped flag drops note-on after STOP + CC64 sustain release + allNotesOff on stop
- tauri: set_bridge_child overwrites managed BridgeProcess state (app.manage is no-op when state exists) so Destroyed handler kills restarted bridge
- ui: stopAllPlayback syncs isPlayingRef/subTabsRef + second transport stop at 150ms; onStatusChange resets __bridgeLoadedChannels at callback start (auto-restart never emits bridge-down); openVstGuiRetry waits for async C++ load before OPEN_GUI; loadVstToBridge uses synth_engine.plugin_path / listPlugins fallback and persists plugin_path on load; shrink track-header Synth/GUI buttons

app/templates/index.html

@@ -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=202608132011" defer></script>
+    <script src="/static/js/app.precompiled.js?v=202608132130" defer></script>
     <link rel="stylesheet" href="/static/css/styles.css?v=202607271016">
     <style>
         :root {