fix: instrument SF3/Sonatina không phát âm thanh - chuyển SF3->SF2, bỏ convert SF2->SF3, sửa converter

app/main.py

@@ -1,4 +1,4 @@
-import os, threading
+import os
 from fastapi import FastAPI
 from fastapi.responses import HTMLResponse
 from fastapi.staticfiles import StaticFiles
@@ -16,7 +16,6 @@ from app.api.v1.ai_presets import router as ai_presets_router
 from app.api.v1.plugins import router as plugins_router
 from app.api.v1.media import router as media_router
 from app.core.auth import seed_admin
-from app.core.soundfont_converter import SoundFontConverter
 from app.core.soundfont_scanner import SoundFontAutoScanner
 
 # Ensure storage directories exist
@@ -63,12 +62,10 @@ async def startup_seed_admin():
 
 @app.on_event("startup")
 async def startup_convert_soundfonts():
-    def _run():
-        try:
-            SoundFontConverter().batch_convert_all()
-        except Exception as e:
-            print(f"[Startup] SoundFont conversion error: {e}")
-    threading.Thread(target=_run, daemon=True).start()
+    # SF2 -> SF3 conversion is disabled: the client FluidSynth WASM cannot decode
+    # Ogg Vorbis (SF3) samples, so converted SF3s would play silence. The download
+    # endpoint serves SF2 when available and converts SF3 -> SF2 on demand instead.
+    pass
 
 @app.on_event("startup")
 async def startup_sf_scanner():