Fix missing 'munch' dep + add detailed error wrapper for ZeroGPU

- Add munch and pydub to requirements.txt (required by Seed-VC modules)
- Add sys.path + chdir fix in GPU worker to find bundled modules
- Wrap convert_voice in try/except to surface full error details
instead of just 'ModuleNotFoundError' class name from ZeroGPU

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

pipeline/inference.py

@@ -186,6 +186,28 @@ def convert_voice(
     Convert voice using Seed-VC zero-shot singing voice conversion.
     Based on the official app_svc.py voice_conversion function.
     """
+    # CRITICAL: Ensure app directory is in sys.path for ZeroGPU worker
+    app_dir = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
+    if app_dir not in sys.path:
+        sys.path.insert(0, app_dir)
+    # Also ensure current working directory is the app directory
+    os.chdir(app_dir)
+
+    try:
+        return _convert_voice_impl(
+            audio_path, reference_path, pitch, index_rate, diffusion_steps
+        )
+    except Exception as e:
+        import traceback
+        tb = traceback.format_exc()
+        # Re-raise as RuntimeError with full details so ZeroGPU forwards the message
+        raise RuntimeError("Seed-VC error: {}: {}\n{}".format(
+            type(e).__name__, str(e), tb[-800:]
+        ))
+
+
+def _convert_voice_impl(audio_path, reference_path, pitch, index_rate, diffusion_steps):
+    """Actual conversion implementation (called from GPU-decorated wrapper)."""
     import soundfile as sf
 
     os.makedirs(OUTPUT_DIR, exist_ok=True)

requirements.txt

@@ -22,10 +22,12 @@ demucs
 # Seed-VC dependencies
 einops
 transformers>=4.40.0
+munch
 pyyaml
 requests
 tqdm
 numba
+pydub
 
 # Vocoder
 bigvgan