fix: _fluid_synth_all_sounds_off + log noteoff return code

- Dùng _fluid_synth_all_sounds_off thay vì CC120
- Log return value của _fluid_synth_noteoff (0=OK, -1=fail)
- Log ch+pitch trong stopNote
- Sửa printErr filter (bỏ check 'stderr')

app/static/js/services/soundfontPlayer.js

@@ -88,7 +88,7 @@
                         },
                         TOTAL_MEMORY: TOTAL_MEMORY,
                         printErr: function (msg) {
-                            if (msg.indexOf('stderr') === -1) console.warn('[FluidSynth:err]', msg);
+                            console.warn('[FluidSynth:err]', msg);
                         }
                     });
 
@@ -305,8 +305,14 @@
         stopNote: function (channel, pitch) {
             if (channel < 0 || channel > 15) return;
             if (_initialized && _fluidModule) {
-                try { _fluidModule._fluid_synth_noteoff(_synthPtr, channel, pitch); } catch (e) {}
-                try { _fluidModule._fluid_synth_cc(_synthPtr, channel, 120, 0); } catch (e) {}
+                console.log("[SonicSF] stopNote ch:", channel, "pitch:", pitch);
+                try {
+                    var r = _fluidModule._fluid_synth_noteoff(_synthPtr, channel, pitch);
+                    if (r !== 0) console.warn("[SonicSF] noteoff returned:", r);
+                } catch (e) { console.warn("[SonicSF] noteoff error:", e); }
+                try {
+                    _fluidModule._fluid_synth_all_sounds_off(_synthPtr, channel);
+                } catch (e) {}
             }
         },