Install soundfont for FluidSynth MIDI audio synthesis

Add fluid-soundfont-gm and timidity packages to setup.sh so Doom's
MIDI music can be synthesized in headless containers. Set SDL_SOUNDFONTS
env var to point to the installed .sf2 file.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: ilya-zakirzyanov

setup.sh

@@ -7,7 +7,7 @@ DIR="learn_doom-simulation"
 # Install system dependencies for ViZDoom audio (OpenAL + FluidSynth)
 if command -v apt-get &>/dev/null; then
   echo "==> Installing system audio libraries..."
-  apt-get update -qq && apt-get install -y -qq libopenal1 libfluidsynth2 2>/dev/null || true
+  apt-get update -qq && apt-get install -y -qq libopenal1 libfluidsynth2 fluid-soundfont-gm timidity 2>/dev/null || true
 fi
 
 echo "==> Cloning $DIR"
@@ -34,6 +34,21 @@ npm install --silent 2>/dev/null
 echo "==> Building client..."
 npx vite build --outDir ../dist 2>/dev/null
 
+# Locate the General MIDI soundfont for FluidSynth MIDI synthesis
+SOUNDFONT=""
+for sf in /usr/share/sounds/sf2/FluidR3_GM.sf2 \
+          /usr/share/soundfonts/FluidR3_GM.sf2 \
+          /usr/share/sounds/sf2/default-GM.sf2; do
+  if [ -f "$sf" ]; then
+    SOUNDFONT="$sf"
+    break
+  fi
+done
+if [ -n "$SOUNDFONT" ]; then
+  echo "==> Using soundfont: $SOUNDFONT"
+  export SDL_SOUNDFONTS="$SOUNDFONT"
+fi
+
 # Start production server (single process, no proxy overhead)
 # ALSOFT_DRIVERS=null lets OpenAL render audio in headless containers without real audio hardware
 echo "==> Starting server on port 3000..."