fix: replace SaveAudio with PreviewAudio in MusicGen workflows

SaveAudio was erroring on 'waveform' key - the AUDIO output from
Musicgen_ node has a different internal structure than what SaveAudio
expects. PreviewAudio is more compatible with Sound Lab's AUDIO format.

Files are still saved to ComfyUI output directory, just through
PreviewAudio instead of SaveAudio.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

comfyui/workflows/text-to-music/musicgen-large-t2m-production-v1.json

@@ -32,7 +32,7 @@
     },
     {
       "id": 2,
-      "type": "SaveAudio",
+      "type": "PreviewAudio",
       "pos": [500, 100],
       "size": [315, 100],
       "flags": {},
@@ -46,9 +46,8 @@
         }
       ],
       "properties": {
-        "Node name for S&R": "SaveAudio"
+        "Node name for S&R": "PreviewAudio"
       },
-      "widgets_values": ["audio/musicgen_large_output"],
       "title": "API Audio Output"
     }
   ],

comfyui/workflows/text-to-music/musicgen-medium-t2m-production-v1.json

@@ -32,7 +32,7 @@
     },
     {
       "id": 2,
-      "type": "SaveAudio",
+      "type": "PreviewAudio",
       "pos": [500, 100],
       "size": [315, 100],
       "flags": {},
@@ -46,9 +46,8 @@
         }
       ],
       "properties": {
-        "Node name for S&R": "SaveAudio"
+        "Node name for S&R": "PreviewAudio"
       },
-      "widgets_values": ["audio/musicgen_medium_output"],
       "title": "API Audio Output"
     }
   ],

comfyui/workflows/text-to-music/musicgen-melody-t2m-production-v1.json

@@ -32,7 +32,7 @@
     },
     {
       "id": 2,
-      "type": "SaveAudio",
+      "type": "PreviewAudio",
       "pos": [500, 100],
       "size": [315, 100],
       "flags": {},
@@ -46,9 +46,8 @@
         }
       ],
       "properties": {
-        "Node name for S&R": "SaveAudio"
+        "Node name for S&R": "PreviewAudio"
       },
-      "widgets_values": ["audio/musicgen_melody_output"],
       "title": "API Audio Output"
     }
   ],

comfyui/workflows/text-to-music/musicgen-small-t2m-production-v1.json

@@ -32,7 +32,7 @@
     },
     {
       "id": 2,
-      "type": "SaveAudio",
+      "type": "PreviewAudio",
       "pos": [500, 100],
       "size": [315, 100],
       "flags": {},
@@ -46,9 +46,8 @@
         }
       ],
       "properties": {
-        "Node name for S&R": "SaveAudio"
+        "Node name for S&R": "PreviewAudio"
       },
-      "widgets_values": ["audio/musicgen_small_output"],
       "title": "API Audio Output"
     }
   ],