Add speaker identification with Resemblyzer

Adds voice-based speaker ID triggered by YAMNet speech detection.
New speaker_id.py module with SQLite-backed voice enrollment and
cosine similarity matching. Endpoints: POST /speakers/enroll,
POST /speakers/enroll-from-mic, GET /speakers, DELETE /speakers/{name}.
Orange LED animation during enrollment.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

sound_id.py

@@ -176,6 +176,7 @@ class SoundClassifier:
             "top_classes": top_classes,
             "dominant_category": dominant,
             "timestamp": now,
+            "audio_float32": audio_f32,
         }
 
     def get_history(self, seconds=30):