revert: Synth button conditional on section items - track can have both

815a6fa hid Synth when track has sections. But a track
can contain both section items AND midi items. Synth
applies to MIDI items regardless of sections. Section
instrument isolation is handled by section clone
nullifying all soundfont fields (9befc20).

app/static/js/app.jsx

@@ -16492,7 +16492,7 @@ const App = () => {
         className: "w-3 h-3"
       })), " FX: ", /*#__PURE__*/React.createElement("span", {
         className: "text-zinc-500 font-normal"
-      }, track.fxType || "None")), (track.midiItems && track.midiItems.length > 0 && (!track.sections || track.sections.length === 0)) && /*#__PURE__*/React.createElement("button", {
+      }, track.fxType || "None")), /*#__PURE__*/React.createElement("button", {
         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", {