Add generated soul core heart model

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

art/generated/soul-core-heart/PROMPTS.md

@@ -27,7 +27,7 @@ Style: stylized low-to-mid poly game asset, chunky readable silhouette, clean sh
 - Model: `fal-ai/hunyuan-3d/v3.1/pro/image-to-3d`
 - Input: `concept.png` (front view only, no extra views)
 - Settings: `generate_type: Normal` (textured), `face_count: 100000`, `enable_pbr: false`
-- Result: `soul-core-heart.glb` (about 20 MB, texture baked in), preview `preview.png`
+- Result: `soul-core-heart.glb` (about 20 MB, texture baked in; not used by the game yet), preview `preview.png`
 
 No text prompt is used in this step. The model only sees the concept image.