fix: named .npz files always start at _001

dog_bark_001.npz, dog_bark_002.npz instead of dog_bark.npz, dog_bark_001.npz.

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

nodes/selva_feature_extractor.py

@@ -72,9 +72,6 @@ def _resolve_named_path(cache_dir: str, name: str) -> str:
     """Return cache_dir/name.npz, incrementing to name_001.npz etc. if the file already exists."""
     # Sanitize: replace path separators so the name stays inside cache_dir
     name = name.replace("/", "_").replace("\\", "_").replace("\x00", "_")
-    base = os.path.join(cache_dir, f"{name}.npz")
-    if not os.path.exists(base):
-        return base
     i = 1
     while True:
         p = os.path.join(cache_dir, f"{name}_{i:03d}.npz")