574c2f885d
- playMidiPreview standalone: thay soundfontRender backend (pyfluidsynth khong co trong bundle -> 501 -> cam) bang playMediaExplorerBridgePreview: allocate channel rieng, bridgeLoad SF2 + loadInstrument, CC0/CC32/PROGRAM, NOTE_ON/OFF theo beat, loop timer; bridge down -> fallback WASM - stopMediaPlayback: NOTE_OFF toan pitch cho channel preview de note khong con ngan sau khi stop