Fix CLAP embedding extraction for transformers 5.x

In transformers 5.x, ClapModel.get_audio_features() returns a
BaseModelOutputWithPooling instead of a raw tensor. The 512-dim
embedding is in .pooler_output[0], not directly indexed. Added
backward-compatible extraction with hasattr check.

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

src/haunt_fm/services/embedding.py

@@ -42,9 +42,14 @@ def embed_audio(audio: np.ndarray, sample_rate: int = 48000) -> np.ndarray:
 
     inputs = _processor(audio=audio, sampling_rate=sample_rate, return_tensors="pt")
     with torch.no_grad():
-        embeddings = _model.get_audio_features(**inputs)
+        output = _model.get_audio_features(**inputs)
 
-    # Flatten to 1-D and normalize
-    emb = embeddings[0].numpy().flatten()
+    # transformers 5.x returns BaseModelOutputWithPooling; extract pooler_output
+    if hasattr(output, "pooler_output"):
+        emb = output.pooler_output[0].numpy()
+    else:
+        emb = output[0].numpy()
+
+    # Normalize to unit vector
     emb = emb / np.linalg.norm(emb)
     return emb