fix: single Synth button opens instrument modal, fix init race condition

- Remove small Synth button (already done earlier)
- Large Synth button now calls openInstrumentSelector (instrument modal)
- Fix _initPromise stale cache: reset to null when init fails
- Module not loaded yet → retries on next select instead of stuck

app/static/js/app.jsx

@@ -15888,7 +15888,7 @@ const App = () => {
       })), " FX: ", /*#__PURE__*/React.createElement("span", {
         className: "text-zinc-500 font-normal"
       }, track.fxType || "None")), /*#__PURE__*/React.createElement("button", {
-        onClick: (e) => { e.stopPropagation(); const btn = e.currentTarget; setInstrumentDropdownTrackId(prev => prev === track.id ? null : track.id); setInstrumentDropdownBtnRect(btn.getBoundingClientRect()); setInstrumentSearchQuery(''); },
+        onClick: (e) => { e.stopPropagation(); openInstrumentSelector(track.id); },
         className: "px-2.5 py-1 bg-zinc-800 hover:bg-zinc-700 text-amber-400 border border-amber-800 rounded text-xs font-bold flex items-center gap-1 max-w-[120px]"
       }, /*#__PURE__*/React.createElement("span", {
         className: "inline-flex items-center shrink-0"

app/static/js/services/soundfontPlayer.js

@@ -44,7 +44,11 @@
             if (_initialized && _synthInstance) return;
             if (_initPromise) return _initPromise;
             _initPromise = (async () => {
-                if (!window.SpessaSynthClass || !window.__SpessaSynthCDN) return;
+                if (!window.SpessaSynthClass || !window.__SpessaSynthCDN) {
+                    console.warn("[SonicSF] SpessaSynth CDN not available. Retrying on next select.");
+                    _initPromise = null;
+                    return;
+                }
                 try {
                     if (audioContext.state === 'suspended') await audioContext.resume();
                     const procUrl = window.__SpessaSynthCDN + "spessasynth_processor.min.js";
@@ -55,6 +59,7 @@
                     _initialized = true;
                 } catch (e) {
                     console.warn("[SonicSF] SpessaSynth init failed:", e);
+                    _initPromise = null;
                 }
             })();
             return _initPromise;