Add sana sprint

[lawrence-cj]

Based on your git commits, here's a concise PR summary:

Add SCM (Smart Consistency Model) Sampler for SANA-Sprint

Summary

Implemented custom SCM sampler with CFG scale support for SANA models in ComfyUI.

Key Changes

• ✅ Initial SCM Implementation: Added basic SANA-Sprint sampling code
• ✅ Single-step Working: Fixed timestep=1, cfg=1 configuration
• ✅ Multi-step Sampling: Extended to support N-step sampling with trigflow timesteps
• ✅ CFG Scale Integration: Successfully implemented CFG scale passing to model forward method

Technical Details

• Custom sample_scm() function with trigflow parameterization (1.57080 → 0)
• ScmModelSampling node for CFG scale injection via transformer_options
• Bypass ComfyUI's standard CFG mixing (KSampler cfg=1.0)
• Direct CFG scale handling in SanaMSCM model

Evolution

1. Started: Basic LCM-based implementation with poor results
2. Fixed: Single-step sampling (timestep=1, cfg=1)
3. Expanded: Multi-step sampling support
4. Completed: Full CFG scale functionality

Usage

SanaCheckpointLoader → ScmModelSampling(cfg_scale=4.5) → KSampler(sampler="scm", cfg=1.0) → Output

Status

🎉 Fully Working - SCM sampling with configurable CFG scale now operational for SANA models.