Default to male voice (am_michael) for the Folio interviewer persona

services/tts_service.py

@@ -28,8 +28,10 @@ import threading
 from collections import OrderedDict
 from pathlib import Path
 
-# American English by default. Kokoro voices: af_heart, af_bella, am_michael, ...
-DEFAULT_VOICE = "af_heart"
+# American English by default. The interviewer persona ("Folio") uses a male
+# voice — am_michael is the highest-rated US male in Kokoro v1.0 (am_fenrir and
+# am_puck are the alternatives; af_heart is the best female if ever needed).
+DEFAULT_VOICE = "am_michael"
 SAMPLE_RATE = 24000
 
 _SERVICE_ROOT = Path(__file__).resolve().parent.parent