refactor: consolidate model management into Ansible playbook

Remove flux/musicgen standalone implementations in favor of ComfyUI:
- Delete models/flux/ and models/musicgen/ directories
- Remove redundant scripts (install.sh, download-models.sh, prepare-template.sh)
- Update README.md to reference Ansible playbook commands
- Update playbook.yml to remove flux/musicgen service definitions
- Add COMFYUI_MODELS.md with comprehensive model installation guide
- Update stop-all.sh to only manage orchestrator and vLLM services

All model downloads and dependency management now handled via
Ansible playbook tags (base, python, vllm, comfyui, comfyui-essential).

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

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

scripts/stop-all.sh

@@ -17,8 +17,6 @@ pkill -f "orchestrator_subprocess.py" || echo "Orchestrator not running"
 
 echo "Stopping model services..."
 pkill -f "models/vllm/server.py" || echo "vLLM not running"
-pkill -f "models/flux/server.py" || echo "Flux not running"
-pkill -f "models/musicgen/server.py" || echo "MusicGen not running"
 
 echo ""
 echo "All services stopped"