fix: thêm logging debug cho noteOn + render + gain explicit

- _fluid_synth_set_gain(1.0) sau khi tạo synth (đảm bảo gain > 0)
- Log noteOn(ch, pitch, vel) mỗi lần play
- Log peak frame đầu tiên khi render > 0.001
- Error log trong catch pushFrame
- Sửa _playNoteFluid: dùng usedBank để xác định ch khi undefined

app/static/js/services/soundfontPlayer.js

@@ -102,6 +102,7 @@
 
                     _synthPtr = _fluidModule._new_fluid_synth(_settingsPtr);
                     if (!_synthPtr) throw new Error("Failed to create FluidSynth synthesizer");
+                    _fluidModule._fluid_synth_set_gain(_synthPtr, 1.0);
 
                     try { _fluidModule.FS.mkdir('/soundfonts'); } catch (e) {}
 
@@ -300,19 +301,27 @@
                 typeof velocity === 'number' ? (velocity > 1 ? velocity : velocity * 127) : 100
             )));
             var ch = channel;
+            var usedBank = 0, usedProg = 0;
             if (synthEngine) {
                 if (ch === undefined) {
                     ch = synthEngine.soundfont_bank === 128 ? 9 : 0;
                 }
+                usedBank = synthEngine.soundfont_bank || 0;
+                usedProg = synthEngine.soundfont_program || 0;
                 try {
-                    _fluidModule._fluid_synth_bank_select(_synthPtr, ch, synthEngine.soundfont_bank || 0);
+                    _fluidModule._fluid_synth_bank_select(_synthPtr, ch, usedBank);
                 } catch (e) {}
                 try {
-                    _fluidModule._fluid_synth_program_change(_synthPtr, ch, synthEngine.soundfont_program || 0);
+                    _fluidModule._fluid_synth_program_change(_synthPtr, ch, usedProg);
                 } catch (e) {}
                 if (channel === undefined) channel = ch;
+            } else if (program !== undefined) {
+                usedProg = program;
+                try {
+                    _fluidModule._fluid_synth_program_change(_synthPtr, ch || 0, usedProg);
+                } catch (e) {}
             }
-            if (ch === undefined) ch = 0;
+            if (ch === undefined) ch = (usedBank === 128 ? 9 : 0);
             var ctx = getCtx();
             var now = ctx.currentTime;
             var delay = (typeof startTime === 'number' && startTime > now) ? (startTime - now) : 0;
@@ -321,6 +330,7 @@
             var self = this;
             var doNote = function () {
                 try {
+                    console.log("[SonicSF] noteOn ch:", ch, "pitch:", midiPitch, "vel:", midiVel);
                     _fluidModule._fluid_synth_noteon(_synthPtr, ch, midiPitch, midiVel);
                     if (delay > 0) {
                         scheduledNote.off = setTimeout(function () {
@@ -443,15 +453,25 @@
         var queueDepth = 0;
         var maxQueue = QUEUE_TARGET;
 
+        var _dbgPeak = 0;
         function pushFrame() {
             if (!Module || !synth || !node) return;
             try {
                 Module._fluid_synth_write_float(synth, block, leftPtr, 0, 1, rightPtr, 0, 1);
                 var leftArr = new Float32Array(Module.HEAPF32.subarray(leftPtr >> 2, (leftPtr >> 2) + block));
                 var rightArr = new Float32Array(Module.HEAPF32.subarray(rightPtr >> 2, (rightPtr >> 2) + block));
+                var peak = 0;
+                for (var si = 0; si < leftArr.length; si++) {
+                    var abs = leftArr[si] > 0 ? leftArr[si] : -leftArr[si];
+                    if (abs > peak) peak = abs;
+                }
+                if (peak > 0.001 && !_dbgPeak) {
+                    _dbgPeak = 1;
+                    console.log("[SonicSF] FIRST AUDIO FRAME peak:", peak);
+                }
                 node.port.postMessage({ type: 'PCM', L: leftArr, R: rightArr }, [leftArr.buffer, rightArr.buffer]);
                 queueDepth++;
-            } catch (e) {}
+            } catch (e) { console.warn("[SonicSF] pushFrame error:", e); }
         }
 
         function fillLoop() {