feat: initial ComfyUI workflow templates extension

- 40 workflow templates (text-to-image, image-to-video, image-to-image,
  text-to-music, upscaling, advanced, nsfw)
- Color-coded placeholder preview images using Pillow
- Template-only extension (no custom nodes)
- Preview generation script for future workflow additions

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

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

example_workflows/diffrhythm-reference-based-v1.json

@@ -0,0 +1,164 @@
+{
+  "last_node_id": 4,
+  "last_link_id": 3,
+  "nodes": [
+    {
+      "id": 1,
+      "type": "LoadAudio",
+      "pos": [100, 100],
+      "size": [300, 100],
+      "flags": {},
+      "order": 0,
+      "mode": 0,
+      "outputs": [
+        {
+          "name": "AUDIO",
+          "type": "AUDIO",
+          "links": [1]
+        }
+      ],
+      "properties": {
+        "Node name for S&R": "LoadAudio"
+      },
+      "widgets_values": [
+        "reference_audio.wav"
+      ],
+      "title": "Load Reference Audio"
+    },
+    {
+      "id": 2,
+      "type": "DiffRhythmRun",
+      "pos": [500, 100],
+      "size": [400, 450],
+      "flags": {},
+      "order": 1,
+      "mode": 0,
+      "inputs": [
+        {
+          "name": "style_audio_or_edit_song",
+          "type": "AUDIO",
+          "link": 1
+        }
+      ],
+      "outputs": [
+        {
+          "name": "AUDIO",
+          "type": "AUDIO",
+          "links": [2, 3]
+        }
+      ],
+      "properties": {
+        "Node name for S&R": "DiffRhythmRun"
+      },
+      "widgets_values": [
+        "cfm_model_v1_2.pt",
+        "Energetic rock music with driving guitar riffs and powerful drums",
+        true,
+        "euler",
+        30,
+        5,
+        "speed",
+        456,
+        "randomize",
+        false,
+        "[-1, 20], [60, -1]"
+      ],
+      "title": "DiffRhythm Reference-Based Generation"
+    },
+    {
+      "id": 3,
+      "type": "PreviewAudio",
+      "pos": [1000, 100],
+      "size": [300, 100],
+      "flags": {},
+      "order": 2,
+      "mode": 0,
+      "inputs": [
+        {
+          "name": "audio",
+          "type": "AUDIO",
+          "link": 2
+        }
+      ],
+      "properties": {
+        "Node name for S&R": "PreviewAudio"
+      },
+      "title": "Preview Generated Audio"
+    },
+    {
+      "id": 4,
+      "type": "SaveAudio",
+      "pos": [1000, 250],
+      "size": [300, 100],
+      "flags": {},
+      "order": 3,
+      "mode": 0,
+      "inputs": [
+        {
+          "name": "audio",
+          "type": "AUDIO",
+          "link": 3
+        }
+      ],
+      "properties": {
+        "Node name for S&R": "SaveAudio"
+      },
+      "widgets_values": [
+        "diffrhythm_reference_output"
+      ],
+      "title": "Save Audio"
+    }
+  ],
+  "links": [
+    [1, 1, 0, 2, 0, "AUDIO"],
+    [2, 2, 0, 3, 0, "AUDIO"],
+    [3, 2, 0, 4, 0, "AUDIO"]
+  ],
+  "groups": [],
+  "config": {},
+  "extra": {
+    "workflow_info": {
+      "name": "DiffRhythm Reference-Based Generation v1",
+      "description": "Generate new music based on a reference audio file while following text prompt guidance",
+      "version": "1.0.0",
+      "author": "valknar@pivoine.art",
+      "category": "text-to-music",
+      "tags": ["diffrhythm", "music-generation", "reference-based", "style-transfer"],
+      "requirements": {
+        "custom_nodes": ["ComfyUI_DiffRhythm"],
+        "models": ["ASLP-lab/DiffRhythm-1_2", "ASLP-lab/DiffRhythm-vae", "OpenMuQ/MuQ-MuLan-large", "OpenMuQ/MuQ-large-msd-iter", "FacebookAI/xlm-roberta-base"],
+        "vram_min": "14GB",
+        "vram_recommended": "18GB",
+        "system_deps": ["espeak-ng"]
+      },
+      "usage": {
+        "reference_audio": "Path to reference audio file (WAV, MP3, or other supported formats)",
+        "model": "cfm_model_v1_2.pt (DiffRhythm 1.2)",
+        "style_prompt": "Text description guiding the style and characteristics of generated music",
+        "unload_model": "Boolean to unload model after generation (default: true)",
+        "odeint_method": "ODE solver: euler, midpoint, rk4, implicit_adams (default: euler)",
+        "steps": "Number of diffusion steps: 1-100 (default: 30)",
+        "cfg": "Classifier-free guidance scale: 1-10 (default: 5 for reference-based)",
+        "quality_or_speed": "Generation mode: quality or speed (default: speed)",
+        "seed": "Random seed for reproducibility (default: 456)",
+        "edit": "Enable segment editing mode (default: false)",
+        "edit_segments": "Segments to edit when edit=true"
+      },
+      "use_cases": [
+        "Style transfer: Apply the style of reference music to new prompt",
+        "Variations: Create variations of existing compositions",
+        "Genre transformation: Transform music to different genre while keeping structure",
+        "Mood adaptation: Change the mood/emotion while maintaining musical elements"
+      ],
+      "notes": [
+        "This workflow combines reference audio with text prompt guidance",
+        "The reference audio is connected to the style_audio_or_edit_song input",
+        "Higher cfg values (7-10) = closer adherence to both prompt and reference",
+        "Lower cfg values (2-4) = more creative interpretation",
+        "Reference audio should ideally be similar duration to target (95s for cfm_model_v1_2.pt)",
+        "Can use any format supported by ComfyUI's LoadAudio node"
+      ]
+    }
+  },
+  "version": 0.4
+}