fix: bypass SpessaSynth AudioWorklet MIDI pipeline for looped voice release

SpessaSynth 4.3.1 bug: looped voices (Tremolo Strings, Trumpet) ignore
release envelope + CC 120 when processed through MIDI message pipeline
(processMessage). Fix: send stopAll directly to worklet via
handleMessage post() bypass, plus noteOn(vel=0) as alternate note-off.

wiki.md

@@ -426,3 +426,8 @@
 - **Tóm tắt thay đổi:** Root cause: `stopNote()` used CC 123 (All Notes Off) which merely enters SoundFont's release envelope. Sustained instruments like Tremolo Strings (GM#44) have 2-5s release tails. Fix: replaced CC 123 with CC 120 (All Sound Off) in `stopNote()` and `stopAll()`. CC 120 sets `voice.isActive = false` immediately, bypassing the release envelope entirely, so the note stops instantly on key release.
 - **Các file ảnh hưởng:** `app/static/js/services/soundfontPlayer.js`
 - **Ghi chú/Test (nếu có):** Test với MIDI keyboard + Tremolo Strings instrument: note tắt ngay khi release key. CC 120 tác dụng lên toàn bộ channel (kill all voices) — phù hợp với keyboard preview use-case.
+
+### [2026-07-27 12:15] Task: Fix SpessaSynth loop voice not releasing (layer 2)
+- **Tóm tắt thay đổi:** CC 120 vẫn không đủ vì SpessaSynth 4.3.1 AudioWorklet có bug: looped voices trong MIDI message pipeline xử lý CC 120 sai (`processMessage`). Fix: thêm `noteOn(ch, pitch, 0)` (MIDI noteOff alternate path) + `_synthInstance.post({channelNumber:ch, type:"stopAll", data:1})` gửi lệnh trực tiếp đến worklet qua `handleMessage` — bypass hoàn toàn MIDI pipeline.
+- **Các file ảnh hưởng:** `app/static/js/services/soundfontPlayer.js`, `app/templates/index.html`
+- **Ghi chú/Test (nếu có):** Cần clear cache browser (index.html cache-bust param updated).