Add pytest suite, unlimited daily cap, and vocal batch generator.

Tests cover curation, Lyria, queue, and API routes. Setting max_new_songs_per_day to 0 disables the limit; generate-batch runs 20 curated multilingual vocal directions.

Co-authored-by: Cursor <cursoragent@cursor.com>

settings.json

@@ -62,7 +62,7 @@
     "new_song_chance": 0.35
   },
   "limits": {
-    "max_new_songs_per_day": 10
+    "max_new_songs_per_day": 0
   },
   "costs": {
     "lyria_pro_usd": 0.08,
@@ -71,7 +71,7 @@
   },
   "lyria": {
     "model": "lyria-3-pro-preview",
-    "vocal_mode": "mix",
+    "vocal_mode": "vocals",
     "language": "auto",
     "singer_profile": "male_baritone",
     "output_format": "mp3",