Normalize Linux audio pipeline to lossless Float32 (skill: lossless-audio-compliance)

- native bridge WAV writers: 16-bit PCM truncation -> IEEE Float32 (fmt 3, bit-exact)
- vendor sheredom_json.h (vst3sdk 3.8.1 lacks moduleinfo/json.h)
- Dockerfile: drop nonexistent sfizz tag v1.2.3
- Python sf.write -> subtype=FLOAT everywhere
- resample_poly -> kaiser(16) window (>=130dB stopband)
- audio_editor._write_wav_lossless(): FLOAT passthrough, TPDF dither only for
  8/16/24-bit final exports
- app.jsx WAV encoders: Float32 default, TPDF dither for integer depths, fix 24-bit
- tests: lossless compliance gate (null test < -140dBFS, float32 format) 9/9 pass
- TASKS_WINDOWS_AUDIO_NORMALIZE.md: Windows-side remaining tasks

app/api/v1/plugins.py

@@ -1249,7 +1249,7 @@ async def soundfont_render(req: SoundfontRenderRequest, current_user: dict = Dep
         )
         from app.core import native_render
         audio = native_render.normalize_audio_peak(audio)
-        sf.write(out_path, audio.T, req.sample_rate)
+        sf.write(out_path, audio.T, req.sample_rate, subtype="FLOAT")
         return {
             "success": True,
             "file_id": os.path.basename(out_path),