V24: fix master-chain crackle, 1s lag, solo bypass

- worklet: FILL 48->24 (PDC 7936 dung), flush protocol khi resume sau interruption
  (clear queue + fade-in/crossfade chi voi block moi), drop block stale
- engine fx_realtime: _flush_input_locked NO-DROP (ring day -> giu pending, cap 2048),
  flush_all() dong bo in/out khi worklet resume
- app.jsx: WS flush_done + flushing guard, fallback timer 500ms
- plugins.py: xu ly {cmd:flush} -> flush_done
- index.html: bump v param

app/templates/index.html

@@ -51,7 +51,7 @@
     <script src="/static/js/services/promptTemplateManager.js?v=202607281039"></script>
     <script src="/static/js/services/undoRedoEngine.js?v=202607290941"></script>
     <script src="/static/js/services/chordTheory.js?v=202608211300"></script>
-    <script src="/static/js/app.precompiled.js?v=202608311300" defer></script>
+    <script src="/static/js/app.precompiled.js?v=202608311400" defer></script>
     <link rel="stylesheet" href="/static/css/styles.css?v=202607271016">
     <style>
         :root {