fix(midi): route MIDI live via masterBus, fix media explorer drag, add action logging

- TrackInstrument: gate native live path (SF/VSTi WASAPI bridge bypassed
  masterBus -> mastering FX + main out VU dead). Fallback to SonicSF WASM
  through masterBus.input; native kept for offline render only.
- MEDIA_LIBRARY_SAMPLES: rename MIDI_Loop_02_Bass/03_Lead/05_Bass to match
  actual /static/midi files (drag was 404 -> parse error).
- Add SonicAppLogger (console + POST /api/v1/logs) wired to: instrument load
  error, VSTi autosample fail, MIDI item -> mastering fx chain, play -> main
  out, drag MIDI errors (media explorer + window explorer).
- Add backend /api/v1/logs endpoint (server-side log, no DB).

app/templates/index.html

@@ -34,11 +34,12 @@
     <script src="/static/vendor/react-dom.production.min.js"></script>
     <script src="/static/js/services/fluidsynthLoader.js?v=202607271245"></script>
     <script src="/static/js/services/runtime.js?v=202608111230"></script>
-    <script src="/static/js/services/api.js?v=202608111230"></script>
+    <script src="/static/js/services/api.js?v=202608111301"></script>
+    <script src="/static/js/services/appLogger.js?v=202608111301"></script>
     <script src="/static/js/services/vstiAutosample.js?v=202608111230"></script>
     <script src="/static/js/services/unifiedMidiRouter.js?v=202608111230"></script>
 <script src="/static/js/services/nativeAudioClient.js?v=202608111230"></script>
-    <script src="/static/js/services/trackInstrument.js?v=202608111230"></script>
+    <script src="/static/js/services/trackInstrument.js?v=202608111301"></script>
     <script src="/static/js/services/audioEngine.js?v=202607271016"></script>
     <script src="/static/js/services/storage.js?v=202608038200"></script>
     <script src="/static/js/services/soundfontStorage.js?v=202607271016"></script>
@@ -50,7 +51,7 @@
     <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=202608111230" defer></script>
+    <script src="/static/js/app.precompiled.js?v=202608111301" defer></script>
     <link rel="stylesheet" href="/static/css/styles.css?v=202607271016">
     <style>
         :root {