comfyui: drop music tool — ACE-Step node interface not standardized

Removed comfyui_music and its workflow. The ACE-Step model runs in
ComfyUI but the node class names differ across custom node packs
(AceStepModelLoader vs native TextEncodeAceStepAudio, etc.), so a
bundled workflow would break for most users.

Documented the reasoning in the plan doc and listed it as an open
question for future work. Users with ACE-Step working can still use
the workflow_json override on any tool.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

tools/_comfyui/workflows/ace-step-music.json

@@ -1,27 +0,0 @@
-{
-  "1": {
-    "class_type": "AceStepModelLoader",
-    "inputs": {
-      "model": "ace_step_v1_3.5b.safetensors"
-    }
-  },
-  "2": {
-    "class_type": "AceStepSampler",
-    "inputs": {
-      "model": ["1", 0],
-      "prompt": "",
-      "lyrics": "",
-      "duration": 30.0,
-      "seed": 42,
-      "steps": 60,
-      "cfg": 3.0
-    }
-  },
-  "3": {
-    "class_type": "SaveAudio",
-    "inputs": {
-      "audio": ["2", 0],
-      "filename_prefix": "openmontage_music"
-    }
-  }
-}